SOUTHAMPTON OCEANOGRAPHY CENTRE

CRUISE REPORT No. 24

RRS DISCOVERY CRUISE 233
23 APR - 01 JUN 1998

A Chemical and Hydrographic Atlantic Ocean Survey:
CHAOS

Principal Scientist
D Smythe-Wright

1999

George Deacon Division for Ocean Processes
Southampton Oceanography Centre
Empress Dock
European Way
Southampton S014 3ZH
UK
Tel: +44 (0)1703 596439
Fax: +44 (0)1703 596204
Email: D.Smythe-Wright@soc.soton.ac.uk

DOCUMENT DATA SHEET

AUTHOR:			SMYTHE-WRIGHT, D et al	
PUBLICATION DATE:	1999
TITLE:			RRS Discovery Cruise 233, 23 Apr-01 Jun 1998. A Chemical 
			and Hydrographic Atlantic Ocean Survey: CHAOS. 
REFERENCE:		Southampton Oceanography Centre Cruise Report, No. 24, 86pp. 

ABSTRACT

RRS Discovery Cruise 233, CHAOS (Chemical and Hydrographic Atlantic Ocean 
Survey) combined a long meridional section notionally along 20°W from 20°N to 
Iceland with a detailed survey of the Rockall Trough. The meridional section was 
designed to i) establish the sources and sinks of halocarbons in subtropical and 
subpolar waters during spring bloom conditions; ii) to examine the decadal scale 
variability in the eastern Atlantic over the last 40 years by repeating the 
northern part of the WOCE A16 line first occupied in 1988 and again in 1993 
(NATL 93), and parts of other sections occupied in 1957, 1973, 1983 and 1991; 
iii). to study the spreading mixing and ventilation rates of Labrador Sea Water, 
Mediterranean Water, and waters of Southern Ocean origin (Antarctic Intermediate 
Water and Antarctic Bottom Water) which extend into the northeast Atlantic. The 
detailed survey of the Rockall Trough comprised 4 zonal sections notionally at 
57°N, 56°N, 54°N and 52°N in order to i) make a detailed study of the water 
masses in the Rockall Trough with particular emphasis on their circulation/ 
recirculation patterns ii) to re-occupy stations along the Ellett line (57°N) to 
continue the time series dating from 1975. The sections were completed with CTD, 
LADCP, tracer chemistry (CFCs, nutrients, oxygen), alkalinity and pH 
measurements to full depth and a suite of halocarbon measurements together with 
sampling for plant pigments and biological species to 200m. Continuous 
measurements of atmospheric halocarbons,pCO2 meteorological measurements, VM -
ADCP, depth, TSG, radiometer SST and navigation data were also made. All 
measurements were made to WOCE standards and the final data submitted 
to the WOCE programme. 

KEYWORDS

ADCP, ALKALINITY, ATLNE, ATMOSPHERIC HALOCARBONS, BIOLOGY, CFC, CHAOS, C02, 
CRUISE 233 1998, DISCOVERY, HALOCARBONS. ICELAND WATERS, LADCP, 
METEOROLOGICAL DATA, METEOROLOGICAL MEASUREMENTS, NORTHEAST ATLANTIC, NUTRIENTS, 
OXYGEN, pH, PLANT PIGMENTS, ROCKALL TROUGH, SISTeR, TRACER CHEMISTRY, TRACERS, 
WOCE

ISSUING ORGANISATION
Southampton Oceanography Centre
Empress Dock
European Way
Southampton S014 3ZH
UK

Copies of this report are available from:
National Oceanographic Library, SOC
PRICE: £19.00
Tel: +44(0)01703 596116
Fax: +44(0)01703 596115
Email:no1@soc.soton.ac.uk

SCIENTIFIC PERSONNEL- Leg I

Name			Role				Affiliation
------------------------------------------------------------------------------
Smythe-Wright, Denise	Principal Scientist		SOC-GDD
Alderson, Steve		CTD processing, LADCP (PI)	SOC-JRD
Bonner, Rob		Salts (PI), CTD technical	SOC-GDD
Bryden, Harry		CTD processing (PI)		SOC-JRD
Davidson, Russell	Pigments (PI), Species (PI)	SOC-GDD
Day, Kate		Oxygen				University of Liverpool
Dimmer, Claudia		Atmospheric gases (PI),		University of Bristol
			Halocarbons
Duncan, Paul		Senior Computing Technician	SOC-RVS
Hart, Virginie		Nutrients (PI)			SOC-GDD
Holliday, Penny		CTD processing			SOC-GDD
Jolly, Dave		Instrumentation			SOC-RVS
Jones, Gwyneth		Data Processing			SOC-ITG
Josey, Simon		Meteorology			SOC-JRD,
Laglera, Luis		pC02 (PI), Alkalinity (PI)	University of Las Palmas
Pascal, Robin		Meteorology, CTD technical	SOC-OTD
Peckett, Cristina	Halocarbons (PI)		SOC-GDD
Poole, Tony		Senior RVS Technician		SOC-RVS
Redbourn, Lisa		ADCP (PI), LADCP		SOC-JRD
Roberts, Rhys		Mechanical			SOC-RVS
Rourke, Lizzy		Oxygen (PI)			SOC-JRD
Rymer, Chris		Mechanical			SOC-RVS
Schazmann, Ben		Pigments, Species		University of Galway
Sheasby, Tom		SST (PI), Oxygen		University of Leicester
Short, John		Computing			SOC-RVS
Smithers, John		CTD technical (PI)		SOC-OTD
Soler-Aristegui, Iris	pH (PI), Halocarbons		SOC, University of Vigo
Somoza-Rodriguez, Maria	pC02, alkalinity, pH		University of Las Palmas
Wilson, Chris		Salts				University of Liverpool

SCIENTIFIC PERSONNEL- Leg 2

Name			Role				Affiliation
------------------------------------------------------------------------------
Smythe-Wright, Denise	Principal Scientist		SOC-GDD
Alderson, Steve		CTD processing, ADCP (PI)	SOC-JRD
Bonner, Rob		Salts (PI), CTD technical	SOC-GDD
Davidson, Russell	Pigments (PI), Species (PI)	SOC-GDD
Day, Kate		Oxygen				University of Liverpool
Dimmer, Claudia		Atmospheric gases (PI),		University of Bristol
			Halocarbons
Duncan, Paul		Senior Computing Technician	SOC-RVS
Hart, Virginie		Nutrients (PI)			SOC-GDD
Jolly, Dave		Instrumentation			SOC-RVS
Jones, Gwyneth (TBC)	Data Processing			SOC-ITG
Josey, Simon		Meteorology (PI)		SOC-JRD
Laglera, Luis (TBC)	pC02 (PI), Alkalinity (PI)	University of Las Palmas
Meggan, Alex		CTD, processing			SOC-JRD
New Adrian		XBT (PI), CTD processing	SOC-JRD
Pascal, Robin		Meteorology, CTD technical	SOC-OTD
Peckett, Cristina	Halocarbons (PI)		SOC-GDD
Redbourn, Lisa		LADCP (PI), ADCP		SOC-JRD
Roberts, Rhys		Mechanical			SOC-RVS
Rourke, Lizzy		Oxygen (PI)			SOC-JRD
Rymer, Chris		Senior RVS Technician		SOC-RVS
Schazmann, Ben		Pigments, Species		University of Galway
Sheasby, Tom		SST (PI), Oxygen		University of Leicester
Short, John		Computing			SOC-RVS
Smithers, John		CTD technical (PI)		SOC-OTD
Soler-Aristegui, Iris	pH (PI), Halocarbons		SOC, University of Vigo
Somoza-Rodriguez, Maria	pC02, alkalinity, pH		University of Las Palmas
Wilson, Chris		Salts				University of Liverpool


SHIPS PERSONNEL

Name		  Rank
------------------------------------------
Avery, Keith	  Master
Gauld, Phil	  Chief Officer
Mackay, Alistair  2nd Officer
Parrotte, Mark	  3rd Officer
Sudgen, Dave	  Radio Officer
Moss, Sam	  Chief Engineer
Clarke, John	  2nd Engineer
Crosbie, Jim	  3rd Engineer
Parker, Phil	  Electrician
Drayton, Mick	  CPO (D)
Lewis, Greg	  PO (D)
Allison, Philip	  SIA
Crabb, Gary	  SlA
Kesby, Steve	  SIA
Thomson, Ian	  SIA
MacLean, Andy	  SlA
Pringle, Keith	  SIA
Dane, Paul	  Senior Catering Officer
Haughton, John	  Chef
Bryson, Keith	  Messman.
Osborn, Jeff	  Steward
Mingay, Graham	  Steward

ACKNOWLEDGEMENTS

Firstly, I should like to thank the Master, Captain Keith Avery, for guiding me 
in my role as first-time Principal Scientist, his advise was much appreciated on 
many occasions. My sincere thanks also go to the officers and crew for their 
unending help throughout the cruise and, in particular, to the second officer, 
Alistair Mackay for his help with station timing/planning. Alistair's expertise 
in estimating, virtually to the half hour, where we would be in a week's time 
was unbelievable and without his help we would not have achieved so much. 

I am most grateful to Melchor Gonzalez-Davila, University of Las Palmas and Aida 
Fernadez-Rios, University of Vigo for arranging equipment and scientific 
personnel for PC02, alkalinity and pH measurements. I am particularly thankful 
to Melchor for quickly arranging a replacement scientist when Stephen Boswell 
was unable to sail because of ill health. Without Melchor's quick response, the 
willingness of Maria Somoza-Rodriguez to join the ship in less than 12 hours, 
and the adaptability of Iris Soler-Aristegui to train Maria and thereby divide 
her time between pH and halocarbon analysis, the chemical results from the 
cruise would not have been so successful. I cannot over-express my gratitude 
to them. 

I am also indebted to Sue Scowston, Andy Louch and Jackie Skelton of RVS 
operations and Rob Bonner for their handling of logistical arrangements; without 
Jacqui's help with travel many of us might never have reached Tenerife to join 
the ship. 

My thanks are also given to the authorities of Mauritania, Algeria, Spain, 
Portugal, Ireland and Iceland for granting us permission to work in their 
territorial waters. So much more was achieved by having access to these waters. 

Finally and, most importantly, I am extremely grateful to the entire scientific 
party for their dedication throughout a particularly long and arduous cruise. 
Without their assistance such a comprehensive data set would not have been 
collected; everyone of them made my first experience as Principal Scientist an 
enjoyable one. 

The cruise was funded by the UK Natural Environment Research Council, 
Southampton Oceanography Centre as a final contribution to the WOCE 
Hydrographic Programme and in 
support of the SASHES (Sources and Sinks of Halogenated Environmental 
Substances) commissioned project. 

Denise Smythe-Wright

Figure 1.1*	CHAOS cruise track showing CTD stations positions. Julian day (1998) 
		is given in normal text, station number in italics.

1	CRUISE DESCRIPTION

1. 1 Details

Cruise Name:	   Chemical and Hydrographic Atlantic Ocean Survey
Designation:	   RRS Discovery Cruise 233
Port calls	   Tenerife to Farlie, Scotland with ship transfers in Vestmannaeyjar 
		   andThorlakshofn, Iceland
Cruise Dates:	   23 April to 1 June 1998
WOCE designation:  AR21

1.2	Outline and Objectives

CHAOS (Chemical and Hydrographic Atlantic Ocean Survey) combined a long 
meridional section along 20°W from 20°N to Iceland with a detailed survey of the 
Rockall Trough. It was a joint effort between the George Deacon (GDD) and James 
Rennell (JRD) Divisions of Southampton Oceanography Centre (SOC). It formed a 
fundamental part of the GDD study of the Sources and Sinks of Halogenated 
Environmental Substances and the JRD core programme Observing and Modeling the 
Seasonal to Decadal Changes in Ocean Circulation.  In addition, we were 
requested by the International WOCE community to complete the section to WOCE 
standards and submit the final data to the WOCE programme because the 20°W 
section was the only long meridional hydrographic section in the eastern North 
Atlantic during the late 1990s. 

The objectives of the cruise were as follows

-  to repeat a section, notionally along 20°W in the Northeast Atlantic, parts 
   of which were occupied previously in 1957, 1973, 1983, 1988 and 1991, in 
   order to examine the decadal scale variability in the eastern Atlantic over 
   the last 40 years. 

-  to establish the sources and sinks of halocarbons in subtropical and subpolar 
   waters during spring bloom conditions. 

-  to study the spreading, mixing and ventilation rates of Labrador Sea Water, 
   Mediterranean Water, and waters of Southern Ocean origin (Antarctic 
   Intermediate Water and Antarctic Bottom Water) which extend into the 
   Northeast Atlantic. 

-  to make a detailed study of the water masses in the Rockall Trough with 
   particular emphasis on their circulation/recirculation patterns. 

-  to contribute to the WOCE baseline survey of the North Atlantic.

1.3	Overview

The cruise commenced in Tenerife on 23 April with a 2.5 days passage leg to 
reach the start of the 20°W section at 20°N. During this time underway 
meteorological, atmospheric and hydrographic measurement were made and there was 
a test station at 26° 13.1' N, 17° 14.7' W in > 4000 m water when all bottles 
were fired at 3500 m. 

We began the 20°W line in the early hours of Sunday 26 April with the first 
station (13415) at 20° 04.0' N, 20° 45.03' W. We then proceeded north-west to 
the 21° 20.0' W meridian working stations at 0.5 degree spacing (stations 13416-
13424). At 24°, 00.0' N we turned north and followed the 21° 20.0' W meridian to 
35° 00.0' N (stations 13425-13466). From there, we made our way diagonally to 
20' 00.0' W (stations 13466-13449) and continued due north from 36° 30.0' N. The 
reason for the dog leg was (a) to avoid Mauritanian territorial waters; despite 
having clearance to work, we were unable to accommodate a Mauritanian observer 
due to pressure on berth space (b) to avoid a number of sea mounts in the region 
23-27°N (c) to cross the top edge of the Maderia Abyssal plain and hence the 
deep flow as obliquely as possible. Between 36° 30.0' N and 52° 00.0' N we 
completed stations 13467-13480 and then turned east to occupy 8 stations along 
52°N to the 500 in contour of the Porcupine Bank (stations 13481-13488). We then 
made our way back to 20°W meridian and continued the 0.5 latitude spacing to 60° 
00.0' N (stations 13489-13504). At this point it was necessary to make headway 
for Iceland to arrive in time for the ship's transfer next day. We completed the 
most northerly station of the section (station 13405) at 63° 19.3' N, 19° 59.3'W 
in the early hours of the morning of 22 May and steamed to the island of 
Vestmannaeyjar and then onto Thorlakshofh, Iceland to collect ships stores and 
exchange personnel. The second Icelandic port call was necessary because, due to 
fog, personnel leaving and joining the ship could not be transferred by air 
between Vestmannaeyjar and the mainland as originally planned.

Leg 2 began by making our way south to pick up the 20°W line at 63° 00.0' N and 
complete the section back to 60° 30.0' N (stations 13506-13511). At this point 
we crossed to Rockall (stations 13512-13520) to close off the flows to and from
the north and during the last 9 days of the cruise completed three zonal 
sections across the Rockall Trough. The first along 57°N (stations 13521-13531) 
or thereabouts was a reoccupation of the Ellett line stations to continue the 
time series dating from 1975. The second and third, notionally along 56°N 
(stations 13532-13543) and 54°N (stations 13544-13553), along with the 52°N 
section completed earlier, where to make a detailed examination of the 
circulation/recirculation patterns of the water masses in the Trough. 

A total of 139 full depth CTD stations were occupied during the cruise. At all 
stations we used the midships gantry to lower the CTD, LADCP and rosette 
sampler. Initially the 10 mm CTD conducting cable was used (stations 13414-
13417); however on the evening of 26 April a collapsed bearing developed in the 
winch and station 13418 was aborted. The wire was changed to the Deep Tow 17 min 
cable using a TOBI swivel and this was used until station 13436 by which time 
the 10 mm winch had been repaired and we changed back to this system for the 
remainder of the cruise. 

Samples were collected at all stations for oxygen, nutrients and salts and at 
the majority of stations for CFC tracers/halocarbons, pigment and speciation 
analysis (although sometimes only from bottles corresponding to the top 200 in). 
In addition samples were collected at every other station for alkalinity and pH 
measurements and at selected stations for DON. A detailed listing of all station 
positions and samples collected is given in Appendix A. Continuous measurements 
through out the cruise included PC02 from the non toxic supply, low molecular 
weight atmospheric halocarbons from the foremast using a length of copper tubing 
and radiometric measurements of the sea surface temperature using the SISTeR 
instrument mounted on the foremast. Data was logged on the ship's computer 
system and processed using PSTAR. Navigation, meteorology, TSG VM-
ADCP and ACCP was operational throughout the cruise. 

2	CTD MEASUREMENTS

2.1	Equipment and operations

The equipment mounted on the CTD frame for this cruise was as follows. 

- C71) Deep 04 WOCE Standard 
- FSI 24 Bottle Rosette Pylon No 2. 
- Chelsea Instruments Transmissometer SN 161/2642/003 
- Chelsea Instruments Fluorometer SN 88/2360/108 
- Simrad Altimeter 200 metre range 
- RDA LADCP 
- FSI 10 Litre Niskin Bottles 
- SIS Digital Reversing Thermometers Nos T401,T714, T995 
- SIS Digital Pressure Meters Nos P6393, P6075, P6394 

During the previous cruise the FSI Rosette pylon No I had performed badly. It 
had failed to fire all positions whilst deployed, but would fire on deck. A 
replacement solenoid had been fitted in position 13 and the unit filled with 
silicon oil prior to the cruise. At this stage it can only be assumed that air 
remained inside the oil filled compartment containing the solenoids. It was 
decided to employ the second pylon for this cruise but this was also 
unsatisfactory. Whilst it would work on a short test lead, communications over 
the full CTD wire were poor. 

The unit appeared to receive commands and fire the bottles but the return 
confirmation signals were corrupted. All efforts to tune the communications 
board failed to improve the situation. The communications board from pylon No 1 
was removed, fitted in unit No 2 and tuned. The unit then performed without 
fault until the last 6 casts when position 7 failed to fire on a number of 
occasions although a confirmation signal was received. 

In all 139 stations were occupied during the cruise. The 10 mm CTD cable was 
used with a swivel/slip ring assembly provided by RVS. 

During the first test cast the oxygen sensor receptacle leaked oil continuously 
so this was replaced with one of a different design. This was incorrectly wired 
up, producing a voltage sufficiently high to affect the other DC analogue 
channels on the CTD. At this point power to the CTD was also lost. The fault was 
traced to the swivel/slip ring assembly. This was removed and the 10 mm CTD 
cable used without a swivel for further deployments. The wiring error was 
corrected but on station 13417 the sensor sensitivity was low. This was replaced 
and from station 13418 onwards worked satisfactorily. 

Beginning with station 13419 the Deep Tow 17 mm cable was used with a TOBI 
swivel for the deeper stations. From station 13437 operations were 
resumed using the 10 min CTD cable. 

SIS pressure meter SN P6075 failed on station 13440. The glass pressure housing 
had cracked and flooded the instrument with sea water. During heavy seas on 
station 13462 the frame containing SIS sensors T989 and P6132 was lost during 
the cast. On recovery of the package on station 13506 power and data connections 
to the CTD were lost. The CTD cable was short circuit at some point near the 
outboard end. Approximately 100 in of cable were cut off and the cable 
terminated. 

The end caps from 3 bottles broke during the cruise and were replaced. Rob 
Bonner also replaced many of the taps as they became tight. 

Apart from the initial problems with the FSI pylon and oxygen sensor, the rest 
of the equipment, both underwater and deck control units worked without fault 
throughout the cruise. 

The cruise data were logged via the RVS level 'A' and SOC DAPS systems with few 
problems. 

John Smithers

2.2	Data capture and processing

The CTD data were captured in dual streams: the SOC DAPS software and the RVS 
Level A. The main stream for processing was DAPS to PSTAR, with the RVS Level A 
used as backup. 

DAPS 
The Data Acquisition and Processing System (DAPS) utilises an Ultra-Sparc SUN 
workstation with an expansion box giving 16 extra serial ports, and is capable 
of real time acquisition/logging of data from a number of shipborne systems. The 
system has been developed at SOC, and is currently capable of logging 
CTD/SeaSoar/Bottles/GPS & Aquashuttle. On D233 it was used for logging CTD data. 

For compatibility with the PEXEC suite of programs, DAPS data files are in ASCII 
format with time in decimal Julian day (with 1 millisecond resolution) in the 
first column. The variables that appear in other columns are configurable by the 
operator. Further compatibility with PEXEC is enabled with the use of 
'dapsascin' which replaces 'pascin' and enables the user to specify a time range 
over which data are read in to PSTAR. Additionally, the utility 'dinfo' is a C-
shell script that identifies data files logged by DAPS and displays the start 
and stop times of each file. 

Unlike the RVS level A, B, C system where single data files for particular 
'instruments' or 'data streams'remain in force for an entire cruise, 
DAPS allows the possibility for creating a new data file for each 'cast' or 
'station' where applicable - e.g. CTD. 

RVS Level A
Data are passed from the CTD deck unit the Level A. The level A averages the raw 
16 Hz data to data at I Hz. Before averaging, the data are checked for pressure 
jumps and median despiked. The gradient of temperature over the I second sample 
of data is calculated. From the Level A, the data are passed to the Level B 
(logging) and then to Level C (archiving). Bottle firings are also logged using 
a separate Level A.

The Level A caused "serial overruns" when accepting and processing data from the
CTD deck unit, but the clock input to the Level A was routinely removed to avoid 
data loss. The internal clock on the CTD Level A is sufficiently accurate over a 
cast if the Level A is allowed to communicate with the clock between stations. 

Temperature
Temperature counts were first scaled by (2. 1) then calibrated using (2.2):

	Traw = 0.0005 x Traw			(2.1)
	T = 0.13079 + 0.999314 x Traw		(2.2)

To correct the mismatch in the temperature and conductivity measurement 
temperature is "sped up" by (2.3): 

		T +,tau dT
	T=	      ---- 			(2.3)
		       dt

where the rate of change of temperature is determined over a one second interval 
and the time constant used was r = 0.25 

Pressure
Raw pressure counts were scaled by (2.4) and then calibrated using (2.5):

	Praw = 0. 1 x Praw			(2.4)
	P = -36.685 + 1.07333 x Praw		(2.5)

Laboratory calibrations show the pressure sensor in DEEP04 shows little 
temperature dependence or pressure hysteresis, so no further corrections 
were made. 

Conductivity
Raw conductivity was first scaled by (2.6) and then calibrated with (2.7).

	Craw = 0-001 x Craw			(2.6)
	C = -0.015 + 0.96743 x Craw		(2.7)

The offset and slope were determined using bottle samples from al-I depths of 
the first seven casts. Over groups of stations small offsets derived from 
samples deeper than 2000 dbar were added to this correction, compensating for 
fluctuations in the CTD and in the bottle sampling.  The corrections applied to 
the offset are listed in Table 2. 1. After the conductivity calibration, the 
salinity residuals (Bottle salinity - CTD salinity) revealed no pressure 
dependence. Table 2.2 gives salinity residuals statistics. 

Oxygen
The oxygen model of Owens and Millard (1985) was used to calibrate the oxygen 
data (2.8)

02 --rho x oxysat(S,T) x (Oc-chi) x exp {alpha x [f x TCTD+(l -f) x Tlag]+beta x P}  (2.8)

where p is the slope, oxysat(S,T) is the oxygen saturation value after Weiss 
(1970), Oc is oxygen current, chi is the oxygen current bias, alpha is the 
temperature correction, f is the weighting of TCM (the CTD temperature) and a 
lagged temperature Tlag and beta is the pressure correction.  Five parameters, 
rho, (alpha, beta, f, chi were fitted for each station. This approach minimises 
the residual bottle oxygen minus CTD oxygen differences but places complete 
reliance on the bottle oxygen being correct. Oxygen concentrations were 
calculated in µmol l^-1.  Stations 13415-13471 have no CTD oxygen data. Table 2.3 
gives the parameters for each station and the postcalibration residual (bottle 
oxygen - CTD oxygen) statistics. 

Transmittance, Fluorescence and Altimetry
Fluorescence was converted to voltages (2.9); this is a calibration of the 
voltage digitiser in the CTD. Transmittance was similarly converted 
to voltages with (2. 10) and further calibrated with (2.11). The altimeter had 
the calibration (2.12) applied. 

	fvolts -5.656 + 1.7267E-4 x fraw + -2.244E-12 x f2raw		(2.9)
	trvolts -5.656 + 1.7267E-4 x trraw + -2.244E-12 x t2 raw	(2.10)
	trans = -0.024 + 4.81 x trvolts					(2.11)
	alt = -234.5 + 7.16E-3 x altraw - 0.95E-10 x altraw		(2.12)

Digital Reversing Temperature and Pressure Meters 
Four digital reversing temperature meters were used, T401, T989, T995 and T714, 
and three reversing pressure meters P6075, P6394 and P6132. T401 and T714 became 
unfunctional after two casts (13415 and 13416), and T989 and P6132 were lost 
along with their frame on cast 13462. P6075 gave readings with a high offset and 
so was removed after cast 13439. T995 and P6394 were moved to position seven on 
the rosette after cast 13439 when the leaking Bottle 3 was replaced. The 
instruments had no calibrations applied. The arrangement of the reversing 
instruments is listed in Table 2.4. 

Penny Holliday and Adrian New

Table 2.1 Corrections to the Conductivity Offset

Station Numbers	Correction
--------------------------
13414 - 13415	 0.0000
13416		 0.0014
13417 - 13420	 0.0000
13421 - 13422	-0.0010
13423 - 13424	-0.0019
13425 - 13428	-0.0027
13429 - 13436	-0.0035
13437 - 13442	-0.0044
13443 - 13456	-0.0057
13457 - 13461	-0.0043
13462 - 13474	-0.0062
13475 - 13484	-0.0067
13485		-0.0020
13486		 0.0000
13487 - 13488	 0.0030
13489 - 13494	 0.0000
13495 - 13500	 0.0030
13501 - 13504	 0.0013
13505 - 13516	 0.0000
13517 - 13522	-0.0038
13523 - 13546	-0.0085
13547 - 13553	-0.0070


Table 2.2 Salinity Residual Statistics

Stations	  Full depth		   Press > 2000 dbar
		 mean	stdev	n	 mean	stdev	n
-------------------------------------------------------------
13415 - 420	 0.0000	0.0016	105/119	-0.0002	0.0007	35/36
13421 - 422	 0.0001	0.0013	44/48	 0.0000	0.0005	15/15
13423 - 424	-0.0002	0.0012	43/48	 0.0000	0.0004	12/13
13425 - 428	-0.0006	0.0013	82/96	-0.0001	0.0007	26/27
13429 - 436	-0.0003	0.0011	181/192	 0.0000	0.0006	59/59
13437 - 442	-0.0005	0.0012	156/168	 0.0000	0.0017	55/55
13443 - 456	-0.0005	0.0014	327/359	 0.0000	0.0012	118/118
13457 - 461	-0.0006	0.0015	112/112	-0.0002	0.0010	29/29
13462 - 474	-0.0006	0.0012	296/306	-0.0001	0.0007	90/90
13475 - 484	-0.0004	0.0014	227/239	 0.0000	0.0011	71/71

Stations	  Full depth		   Press > 1000 dbar
		 mean	stdev	n	 mean	stdev	n
-------------------------------------------------------------
13485 - 488	-0.0006	0.0018	49/64	 0.0003	0.0010	20/20
13489 - 494	-0.0007	0.0016	93/102	 0.0001	0.0008	37/37
13495 - 500	-0.0011	0.0018	67/79	 0.0000	0.0015	13/13
13501 - 504	-0.0004	0.0012	76/80	-0.0002	0.0006	38/38
13505 - 516	-0.0011	0.0018	146/165	-0.0009	0.0013	48/50
13517 - 522	-0.0014	0.0016	62/64	 0.0001	0.0028	5/5
13523 - 546	-0.0017	0.0016	323/351	-0.0003	0.0013	104/105
13547 - 553	-0.0014	0.0018	97/106	-0.0003	0.0014	40/43

Stations	  Full depth		   Press > 2000 dbar
		 mean	stdev	n		mean	stdev	n
-----------------------------------------------------------------------
13415 - 553	-0.0008	0.0015	2449/2669	-0.0001	0.0008	578/585

Note: excludes residuals outside the range ± 0.005 psu

Table 2.3a Oxygen Coefficients

Station	  rho	 alpha		  beta		   f		 chi
----------------------------------------------------------------------
13419	3.8932	-0.0001856	 0.03047	-0.15471	0.0000
13420	4.3942	-0.0001994	 0.03201	-0.16644	0.0000
13421	4.3549	-0.0002106	 0.03297	-0.17140	0.0000
13422	4.5721	-0.0002150	 0.03372	-0.17447	0.0000
13423	4.0884	-0.0001978	 0.02830	-0.16046	0.0432
13424	4.3194	-0.0001953	 0.03061	-0.16686	0.0000
13425	4.2225	-0.0002006	 0.02956	-0.16762	0.0000
13426	3.9116	-0.0002164	 0.02510	-0.16735	0.5695
13427	4.0425	-0.0001972	 0.02891	-0.16268	0.0000
13428	4.0133	-0.0002246	 0.02568	-0.17070	0.4714
13429	4.0249	-0.0002044	 0.02744	-0.16450	0.0000
13430	4.0479	-0.0001962	 0.02787	-0.16263	0.0000
13431	4.0061	-0.0001899	 0.02815	-0.15898	0.0031
13432	4.0062	-0.0002112	 0.02650	-0.16682	0.0586
13433	4.0769	-0.0002072	 0.02770	-0.16608	0.0014
13434	4.2365	-0.0002105	 0.02909	-0.17056	0.0092
13435	4.1219	-0.0002040	 0.02800	-0.16572	0.0000
13436	4.0620	-0.0001910	 0.02888	-0.16029	0.0014
13437	4.0909	-0.0002143	 0.02893	-0.16921	0.0000
13438	4.1174	-0.0001969	 0.02898	-0.16194	0.0000
13439	4.1636	-0.0002015	 0.02801	-0.16528	0.0000
13440	4.1699	-0.0002357	 0.02719	-0.17660	0.0000
13441	4.1699	-0.0002357	 0.02719	-0.17660	0.0000
13442	4.0755	-0.0001865	 0.02907	-0.15843	0.0000
13443	4.1102	-0.0001937	 0.02877	-0.16176	0.0000
13444	3.8414	-0.0001925	 0.02518	-0.15583	0.0000
13445	4.1128	-0.0002541	 0.02441	-0.18169	0.0681
13446	4.1730	-0.0002086	 0.02736	-0.16823	0.0000
13447	4.1933	-0.0001994	 0.02898	-0.16504	0.0000
13448	4.1099	-0.0002174	 0.02683	-0.17023	0.0000
13449	4.0538	-0.0002404	 0.02471	-0.17661	0.1383
13450	4.1529	-0.0001928	 0.02915	-0.16101	0.0000
13451	4.1935	-0.0002424	 0.02626	-0.17906	0.0105
13452	4.1438	-0.0001901	 0.03086	-0.16028	0.3694
13453	4.1168	-0.0002160	 0.02722	-0.16866	0.2521
13454	3.9595	-0.0002903	 0.02077	-0.18933	0.2276
13455	4.0358	-0.0002717	 0.02263	-0.18464	0.2081
13456	4.0621	-0.0001977	 0.02685	-0.16172	0.1287
13457	3.8924	-0.0002914	 0.01785	-0.18809	0.0968
13458	4.0993	-0.0001883	 0.02878	-0.15783	0.0000
13459	3.8292	-0.0002274	 0.02456	-0.16368	0.6503
13460	4.0668	-0.0001871	 0.02939	-0.15377	0.0000
13461	4.0643	-0.0001928	 0.02637	-0.15983	0.2510
13462	4.0977	-0.0001883	 0.03107	-0.16010	0.4547
13463	4.1558	-0.0002025	 0.02733	-0.16484	0.2028
13464	4.0706	-0.0002162	 0.02739	-0.16768	0.4301
13465	4.1240	-0.0001788	 0.02888	-0.15568	0.1953
13466	4.0426	-0.0001800	 0.02728	-0.15447	0.2726
13467	4.0408	-0.0001607	 0.03356	-0.14600	0.0653
13468	4.0369	-0.0001877	 0.02775	-0.15672	0.2071
13469	4.0035	-0.0001144	 0.03494	-0.12143	0.0275
13470	4.0197	-0.0001421	 0.03170	-0.13586	0.0000
13471	4.0232	-0.0001466	 0.03053	-0.13795	0.1418
13472	4.0857	-0.0001278	 0.03401	-0.13049	0.0000
13473	4.1015	-0.0001274	 0.03181	-0.12841	0.0100
13474	4.0157	-0.0001483	 0.03049	-0.13802	0.1477
13475	3.9584	-0.0001510	 0.03071	-0.13682	0.2261
13476	4.1159	-0.0001455	 0.03258	-0.14008	0.1640
13477	4.1262	-0.0001463	 0.03192	-0.13945	0.0004
13478	4.1069	-0.0001431	 0.03367	-0.13837	0.0000
13479	4.0902	-0.0001093	 0.03669	-0.12142	0.0000
13480	4.1136	-0.0001119	 0.03776	-0.12302	0.0000
13481	4.1311	-0.0001563	 0.03044	-0.14516	0.2961
13482	4.1776	-0.0001641	 0.03053	-0.14996	0.0000
13483	4.0824	-0.0001313	 0.03289	-0.13307	0.0000
13484	4.1391	-0.0001575	 0.03208	-0.14842	0.1757
13485	4.1439	-0.0001716	 0.02891	-0.15169	0.1189
13486	3.8527	-0.0001686	 0.02811	-0.13986	0.1204
13487	4.0279	-0.0001777	 0.02969	-0.14977	0.3983
13488	3.3404	-0.0003459	 0.01240	-0.15611	0.0000
13489	3.9931	-0.0001617	 0.02857	-0.14464	0.0000
13490	4.1579	-0.0001374	 0.03321	-0.13760	0.0000
13491	4.3517	-0.0001181	 0.03515	-0.13886	0.0000
13492	3.7728	-0.0002332	 0.01913	-0.15501	0.2599
13493	4.3513	-0.0001581	  0.0337	-0.15052	0.0366
13494	3.9099	-0.001948	 0.02343	-0.15150	0.0458
13495	3.4606	-0.0002928	 0.01306	-0.15687	0.1699
13496	4.6935	-0.0000228	 0.04854	-0.11366	0.0000
13497	4.6935	-0.0000228	 0.04854	-0.11366	0.0000
13497	4.7521	-0.0000478	 0.04780	-0.12027	0.0000
13498	3.3632	 0.0000086	 0.03375	-0.04747	0.0000
13499	3.6820	-0.0003548	 0.00775	-0.18266	0.2297
13500	4.5651	-0.0001527	 0.03715	-0.15295	0.0000
13501	3.9879	-0.0001515	 0.02919	-0.13759	0.1264
13502	3.8229	-0.0001772	 0.02042	-0.14646	0.1569
13503	3.8498	-0.0001386	 0.02686	-0.12758	0.0000
13504	3.2965	-0.0002900	-0.00399	-0.17312	0.3008
13505	3.4024	-0.0000449	 0.03014	-0.07075	0.1081
13506	3.7764	-0.0001316	 0.02749	-0.11852	0.0417
13507	3.8185	-0.0001961	 0.02371	-0.15160	0.1007
13508	4.6195	-0.0000583	 0.04751	-0.12374	0.0000
13509	3.8623	-0.0001574	 0.02409	-0.13808	0.0000
13510	3.7361	-0.0001595	 0.02336	-0.13360	0.1585
13511	3.8804	-0.0001644	 0.02312	-0.14213	0.0697
13512	3.9643	-0.0001293	 0.02814	-0.12476	0.0000
13513	3.8692	-0.0001898	 0.02080	-0.15195	0.1830
13514	4.3931	-0.0000730	 0.04343	-0.11805	0.0000
13515	3.3918	-0.0001290	 0.01603	-0.12426	0.0000
13516	3.5261	-0.0001078	 0.02302	-0.11126	0.0000
13517	3.5153	-0.0001203	 0.02410	-0.11225	0.0000
13518	4.2182	-0.0001225	 0.03380	-0.13987	0.0000
13519	3.6136	-0.0001329	 0.02157	-0.13206	0.0000
13520	3.9504	-0.0001220	 0.03248	-0.12166	0.0000
13521	3.1881	 0.0001937	 0.02806	-0.05360	0.2643
13522	3.3952	-0.0001548	 0.01936	-0.12167	0.4933
13523	3.9544	-0.0000611	 0.04085	-0.09102	0.0000
13524	3.8150	 0.0001927	 0.06369	 0.07245	0.3070
13525	3.8281	-0.0000916	 0.03265	-0.10744	0.0000
13526	1.7011	 0.0002088	 0.03409	 0.39984	0.2059
13527	4.0960	-0.0000952	 0.03674	-0.11837	0.0000
13528	3.7897	-0.0001508	 0.02689	-0.13079	0.0000
13529	3.3870	-0.0001964	 0.01727	-0.13159	0.0000
13530	2.9358	-0.0001760	 0.00391	-0.12286	0.5878
13531	3.3850	 0.0001800	 0.09408	 0.27848	0.0109
13532	3.6923	-0.0001046	 0.01919	-0.14528	0.0000
13533	3.2612	-0.0002290	-0.00231	-0.18323	0.2069
13534	3.7805	-0.0000975	 0.03190	-0.10884	0.0000
13535	4.1090	-0.0000711	 0.03983	-0.10740	0.0000
13536	3.8213	-0.0001018	 0.03201	-0.11186	0.0000
13537	3.8285	-0.0001232	 0.02970	-0.12054	0.1175
13538	3.9003	-0.0001523	 0.02655	-0.13830	0.0000
13539	4.0896	-0.0000817	 0.03780	-0.11272	0.0000
13540	4.6298	-0.0000838	 0.04377	-0.13271	0.0000
13541	3.5900	-0.0002540	 0.01452	-0.16208	0.0000
13542	3.7086	-0.0001440	 0.02464	-0.13129	0.0000
13543	3.3039	-0.0001773	 0.01221	-0.13658	0.0000
13544	3.4017	-0.0001789	 0.01748	-0.13378	0.0000
13545	5.2387	 0.0001792	 0.07954	-0.01202	0.0000
13546	3.7665	-0.0001538	 0.02566	-0.13461	0.1568
13547	4.0605	-0.0001715	 0.02809	-0.15143	0.1709
13548	3.8891	-0.0001981	 0.02359	-0.15792	0.2760
13549	4.0338	-0.0001188	 0.03369	-0.12926	0.0000
13550	3.7553	-0.0002015	 0.02193	-0.15195	0.1625
13551	0.0114	 0.0001507	 0.05808	 0.96337	0.6617
13552	3.2916	-0.0001415	 0.01993	-0.11285	0.0000

Table 2.3b Calibrated oxygen residuals (bottle oxygen - CTD oxygen)

Stations	  Full depth		  Press > 1000 dbar
		 mean	stdev	n	 mean	stdev	n
---------------------------------------------------------------
13415 - 420	 0.6684	4.9390	43/48	 0.1135	1.8464	19/20
13421 - 422	-0.1281	4.2899	46/48	 0.2648	1.8788	23/23
13423 - 424	-0.0345	2.7713	46/48	 0.3719	1.5373	20/20
13425 - 428	 0.0149	4.5643	94/94	 0.4678	2.2099	41/41
13429 - 436	 0.0087	2.4734	189/189	 0.2762	1.8379	88/88
13437 - 442	-0.1336	2.9171	163/163	 0.1313	1.7038	80/80
13443 - 456	-0.0805	2.9594	322/346	-0.0365	2.1512	160/171
13457 - 461	-0.0096	3.3870	106/106	 0.1592	1.5676	50/50
13462 - 474	-0.0133	2.8616	290/290	 0.1235	1.8900	134/134
13475 - 484	 0.1462	3.4489	225/227	 0.1406	1.2800	109/109
13485 - 500	-0.0006	3.0840	231/232	 0.3436	1.6723	68/68
13501 - 520	 0.0276	3.9810	309/313	 0.3155	2.0037	103/103
13521 - 553	-0.0276	2.9369	475/479	 0.0660	1.5887	148/148

13415 - 553	 0.0063	3.1595  2449/2542 0.1937 1.9791 1021/1033

Note: excludes residuals outside the range ± 15 µmol l^-1

Table 2.4 Arrangement of Reversing Temperature and Pressure Meters

Stations	Bottle	Instrument
-----------------------------------------
13415		1	T401, T989, P6075
		3	T995, P6394
13416		1	T401, T989, P6075
		3	T995, P6394
		11	T714, P6132
13417 - 13439	1	T989, P6075
		3	T995, P6394
		11	P6132
13440 - 13462	1	T989, P6132
		7	T995, P6394
13463 -		7	T995, P6394

2.3	Post-cruise laboratory calibration

The calibration data used during D233 were from laboratory calibrations in July 
1996. The post cruise calibrations carried out in October 1998 produced the 
following data: 

		scale	offset	linear
----------------------------------------
Pressure	0.1	-38.3	1.0738
Temperature	0.0005	0.13121	0.99928


The difference in pressure due to the linear term is only 2.6 dbar at full 
scale. The difference in temperature due to the offset is only 0.42 m°C and the
linear terms differ by 1.65 m°C at full scale. It was concluded that these 
differences were sufficiently small that no additional calibrations need be 
applied. 

S. Cunningham

2.4	References

Owens, W. B. and R.C.Millard, 1985: A new algorithm for CTD oxygen calibration. 
  J. Phys. Oceanogr., 15 621-631
Weiss, R. F., 1970: The solubility of nitrogen, oxygen and argon in water and 
  seawater.
Deep-Sea Res. 17 721-735.

3 	LOWERED ADCP MEASUREMENTS

The Lowered Acoustic Doppler Profiler (LADCP) is an RDI 150 kHz BroadBand ADCP 
(phase 111) with 30 degree beam angles. It is mounted vertically within the CTD 
frame with the bottom of the transducers protected by the base of the frame. The 
LADCP was installed on the CTD frame at the beginning of the cruise. It had been 
hoped to use a rechargeable power pack to avoid the regular removal and 
replacement of batteries.  Unfortunately the enclosing pressure case for the 
rechargeable system could only be used down to 1000 db. Ten alkaline battery 
packs were on board at the start of the cruise including two part used ones. Two 
further packs were brought out by personnel joining the ship from Iceland for 
the last week of the cruise. To change the batteries, the pressure case was 
either removed from the frame and batteries removed in the lab, or in quiet sea 
states where no risk of spray was present, the case was left on the frame and 
the batteries removed. The latter method impeded sampling on one occasion 
because of the danger of wetting exposed cables. These slight difficulties will 
be avoided in future by use of the rechargeable system. 

A few minutes before each cast, a command file was downloaded to the unit from a 
PC in the deck lab via a serial link. On this cruise the same command file was 
used throughout. A listing is given in Appendix C. It was decided at the 
beginning of the cruise to use bottom tracking throughout. This reduces the 
number of water track pings, but is justified because it allows a second 
independent estimate of the bottom current to be made. At regular intervals the 
instrument emits a bottom ping to test for range. Once the bottom was found the 
instrument recorded the velocity of the ground with respect to the package. It 
was hoped that this would provide a check of the quality of the absolute 
velocity data calculated by the more round about route described below. 

The data were recorded internally and downloaded at the end of each cast by 
connecting a data link to the package from the PC. RDI utilities BBTALK and BBSC 
were used to interrogate the profiler and to download data to the PC. Power is 
supplied to the profiler via the serial cable in order to conserve the battery 
pack. 

Data were transferred to the UNIX workstations via PC-NFS and then processed 
using a combination of PERL scripts and MATLAB m-files deve-loped by Eric Firing 
at the University of Hawaii. Processing was done in a number of steps which are 
briefly described:

i.   The binary data were first scanned to find useful information from the cast
     such as time at the surface, time at the bottom and number of ensembles.
ii.  The data were then read into a CODAS database. Magnetic variation and 
     position were added to the database at this stage.
iii. When CTD data were available, the pressure temperature and salinity data 
     were added to the database in order to correct for the variation of sound 
     speed with depth.
iv.  Absolute velocities were then found by calculating horizontal velocity 
     shear to eliminate package motion, integrating with time to calculate the 
     barotropic term and then merging with navigation data to remove the motion 
     of the ship.

Bottom velocity data are not included in this processing path and had to be 
extracted manually from the binary file on the PC and processed separately from 
the water track data. Preliminary comparisons were made between the resulting 
velocities and the near bottom velocities extracted from the absolute water 
track data. No clear interpretation was achieved and more work is required here. 

Comparisons with geostrophic profiles from the CTD data for the 20°W line are 
shown in Figure 3.1*.  A horizontal line is drawn on each plot at 3210 m which is 
the level at which the

Figure 3.1*	Comparison of LADCP data with geostrophic profiles calculated from 
		CTD data

geostrophic velocity is assumed to be zero. If the water depth is shallower than 
3210 m, a zero velocity is assumed at the bottom. 

Steve Alderson, Lisa Redborn and Chris Wilson

4	VESSEL MOUNTED ADCP MEASUREMENTS

4.1	Description and Processing

The instrument used was an RDI 150 kHz unit, hull-mounted approximately 2 m to 
port of the keel of the ship and 33 in aft of the bow at the waterline. Data 
Acquisition Software (DAS), version 2.48, was run on a PC to acquire the data. 
With the exception of a few interruptions (see Problems section below) the 
instrument operated continuously from JD 114 to JD 15 1 in the water-tracking 
mode, and set to use 3 beam solutions for determining velocities as beam 3 (the 
forward beam) was not working. Ping data were averaged by the DAS into 2 minute 
ensembles, and 64 x 8 m depth bins were used for the entire cruise with a depth 
offset of 13 m included in the processing to allow for the ship's draught and 
the 'blank after transmit' period.

Daily Processing

-  Acquisition of ADCP water-tracking velocities from Level C RVS files and 
   conversion to PSTAR format using the PSTAR program adpexecO. 

-  Correction of the times of each ADCP ensemble to account for the linear, 18 
   second per 24 hour drift of the PC clock using program adpexec 1. 

-  Correction of ADCP heading data (which the DAS reads from the ship's 
   gyrocompass) using the Ashtech minus gyro heading differences (program 
   adpexec2). 

-  Calibration of the shear profiles, taking account of errors in signal 
   amplitude and transducer alignment using a working calibration 
   determined by a 'zig-zag' run in water-tracking mode at the end of cruise 
   D232 (see Calibration section below). This was done with program adpexec3.

-  Merging velocity profiles with navigation fixes obtained from the GPS4000 
   navigation files to effectively remove the ship's speed from the ADCP 
   velocities, thus giving absolute velocities (program adpexec4).

-  Separation of each day's ADCP data into 'on station' and 'underway' files. 
   Each on station file corresponded to a CTD station and the velocities in 
   these files were plotted as vectors, averaged over the period of time the 
   ship held station and plotted against LADCP velocity profiles for comparison. 

4.3. Calibration

The ADCP is calibrated to take account of the orientation of the transducer 
mounted in the hull (the transducer orientation is intended to be fore-aft). 
Ideally, the ADCP's bottom-tracking mode is employed in shallow (<500 m) water 
to determine the amplitude factor, A, and the alignment angle error, 0. However, 
the absence of beam 3 meant that the bottom-tracking mode of ADCP operation was 
unavailable throughout this cruise. Instead, a total of three zigzag runs in 
regions known to have fairly uniform currents were used to calibrate the ADCP; 
one conducted at the end of cruise D232 and the other 2 conducted on JDs 137 and 
151 of cruise D233. 

During each zig-zag run, the Bridge were asked to make an initial turn of 44° 
(either to port or starboard as preferred) away from the base course at between 
10 to 15 seconds past the hour. The new heading was maintained at a steady speed 
of 10 knots for 20 minutes. At 20 minutes past the hour, a 90° turn back towards 
the base course was made, and thereafter alternate 90° turns were completed, 
with 20 minutes steaming between each turn. As far as possible, the same speed 
through the water was maintained throughout, and the entire calibration run 
lasted for about 3 hours in each case. 

Data from the zig-zag runs were processed as described above but with A set to 1 
and ø set to 0° in adpexec3. Data recorded during the ship's turns were 
discarded, and the components of ship's velocity and ADCP velocity (i.e. 'water 
past the ship') were each averaged together for each of the 'zigs' or 'zags' 
between turns. The differences in each of these four averaged components were 
then calculated for before and after each turn such that: 

adpe =  difference between averaged east-west component of ADCP velocity before 
	and after turn. 

adpn =  difference between averaged north-south component of ADCP velocity 
	before and after turn. 

ve =	difference between averaged east-west component of ship's velocity before 
	and after turn. 

vn =	difference between averaged north-south component of ship's velocity 
	before and after turn.

So, a zig-zag run comprising eight 90° turns produces eight different values of 
each of these 4 quantities.

Equations 4.1 and 4.2 are then used to find ø and A: 

         (ve x adpn) - (vn x adpe)
tan ø = --------------------------------		(4.1)
         (vn x adpn) + (ve x adpe)

         (vn x adpn) + (ve x adpe)			(4.2)
A =    -   ------------------------------
         cos ø x (adpe^2 + adpn 2)

The 8 values of ø and A were then averaged to give the best estimate of the true 
amplitude factor and transducer misalignment angle. The calculations were made 
using data from several bin depths to further reduce the likelihood of errors. 

The zig-zag calibration at the end of D232 gave average values of ø and A as 
2.64° (with an sd of 0.0l°) and 0.9917 respectively and these values were used 
in adpexec3 to calibrate all data from this cruise. Data from the zig-zag run on 
JD 137 of this cruise have not been worked up due to the poor quality of ADCP 
data acquired on that day (see Problems below). The final run, conducted on the 
last day of the cruise (JD 151) will be worked up ashore. 

4.4	Problems

Gaps in the otherwise continuous ADCP data set were as follows:

-  JD 120, 19:17 to JD 121 04:45: ADCP was still working but logging to level C 
   had stopped.
-  JD 122, 17:20 to 17:30: ADCP was interrupted to retrieve missing data for the 
   previous day from raw files on the P.C.'s hard disk.
-  JD 127, 08:35 to 09:35: Power cut.
-  JD 139, 04:37 to 04:40 ADCP interrupted to change settings in DAS.
-  JD 140, 12:00 to 12:40: ADCP interrupted to change settings in DAS.
-  JD 141, 07:30 to 08:42: ADCP stopped for testing.
-  JD 144, 11:45 to 11:55: ADCP stopped to check settings in DAS.

The majority of these interruptions were necessary as a result of a persistent 
problem occurring with the DAS software prior to the data being logged in the 
RVS files.

As beam 3 was known not to be working, the DAS software was set to calculate 3 
beam velocity solutions from the start of the cruise. However, it appeared that 
the DAS software was still using 4 beam solutions at certain times, such that 
'bad' data from beam 3 were included which subsequently degraded the calculated 
velocities. The use of 4 beam solutions was identified in the ADCP data files by 
the presence of non-zero error velocities (error velocities being only 
determinable when all 4 beams are used). Throughout the cruise, the occasional 
non-zero error velocity in the data files occurred, but during the period from 
JD 133 to JD 145, the percentage of 4 beam solutions being used was large enough 
to produce many spurious velocities which considerably degraded the data set. JD 
137 was perhaps the worst day in terms of poor data quality during this period. 

4 beam solutions were particularly prevalent at depth and in the 'underway' data 
between CTD stations. On station velocity profiles were still reliable to about 
150 in depth, as confirmed by comparisons with LADCP data. At depths greater 
than 150 in, large changes in current velocity (up to 60 cm s^-1) appeared to 
occur simultaneously throughout the water column whenever the ship's speed 
changed, which was clearly erroneous. 

The abundance of 4 beam solutions at depth may indicate that whenever the DAS 
software receives back-scattered signals which it considers to be too low, it 
listens to all 4 beams in an attempt to improve the signal to noise ratio, and 
subsequently calculates velocity using ping data from all 4 beams. However, this 
problem will require further investigation ashore. 

Lisa Redbourne, Steve Alderson, Harry Bryden , Dave Jolley

5	NAVIGATION DATA

5.1	Differential GPS4000

Differential GPS4000 navigation data (ship position, heading, speed over ground, 
satellite fix parameters) were acquired every second throughout the cruise, 
giving the ship's position to within 5 in. 

Daily Processing: 

-  Acquisition of GPS4000 data from RVS files using the gpsexec0 program.
-  Quality control of data in which data are deleted wherever poor positioning 
   accuracy is indicated by satellite fix parameters. 
-  Averaging ship velocity data into 2 minute bins for subsequent merging with 
   ADCP data.

Data Quality
The percentage of 'good' data acquired during a 24 hour period ranged from a 
minimum of 97.5% on JD 108 to a maximum of 99.8% on JD 103.

5.2	Ship's Gyrocompass

Two SG Brown gyrocompass units are installed on the bridge. Ship heading was 
logged every second via a level A microprocessor. 

Daily Processing
-  Acquisition of gyro heading data from RVS files using the gyroexecO program.

Data Quality
The percentage of 'good' data acquired during a 24 hour period ranged from a 
minimum of 99. 1 % on JD 96 to a maximum of over 99.9% on JD 99.

5.3	Ashtech 3DF GPS Attitude Determination

The Ashtech 3DF GPS is a system comprising four satellite receiving antennae 
mounted on the boat deck and the roof of the bridge with a receiver unit in the 
bridge itself. Every second the Ashtech measures ship attitude (heading, pitch, 
roll) and these data are used in post-processing to correct ADCP current 
measurements for 'heading error'. This post-processing is necessary as the ADCP 
uses the less accurate but more continuous ship's gyro headings to resolve east 
and north components of current. With each attitude acquired are measures of the 
maximum measurement rms error and maximum baseline rms error which permit poorly 
determined attitudes to be flagged during processing. 

Daily Processing: 
-  Acquisition of Ashtech data from RVS files using the ashexec0 program.
-  Quality control of Ashtech data using ashexec 1.
-  Averaging into 2 minute bins to be compatible with ADCP data and 
   determination of the 'aghdg' parameter (the correction applied to gyro 
   headings) using ashexec2. 
-  Plotting daily time series of a-ghdg and manually editing out any remaining 
   outliers from the data using PLXYED and ashexec3. 

Data Quality
The percentage of 'good' data acquired during a 24 hour period ranged from a 
minimum of 87.7% on JD 107 to a maximum of 98.3% on JD 103. Manual editing was 
required on JD's 103, 104, 105, 107 and 108 with a maximum of 9, 2 minute 
averaged data cycles being removed on JD 107. The largest 
gap in a-ghdg data was also on JD 107 and lasted approximately 2 hours. 

5.4	Problems with Navigation Data

A power cut of approximately 30 minutes from 08:35 to 09:05 on JD 127 caused all 
navigation instruments to stop logging during that period. On the same day, the 
Ashtech stopped logging for 4 hours from 05:40 to 09:40, a loss of data 
initially unrelated to the power cut. It also stopped logging for 10 minutes at 
about 20:00 on JD 138. 

Lisa Redbourne and Steve Alderson

6 	METEOROLOGICAL MEASUREMENTS

6.1	Aims

The primary goals of the surface meteorological and radiative flux measurements 
made on D233 were: 

i.   To evaluate sources of error in the downwelling longwave flux as measured 
     by an Eppley pyrgeometer using a circuit that allows the temperatures of 
     various components of the pyrgeometer to be recorded. 

ii.  To investigate the dependence of the corrected downwelling longwave on the 
     amount of cloud cover, the air temperature and the humidity, and to develop 
     a new parameterisation for this flux if existing ones prove insufficient. 
     The large range of latitude, 20 - 63.5 °N, covered during the cruise 
     provided an ideal opportunity for this investigation to be carried out 
     under a wide variety of atmospheric conditions. 

In addition, measurements of various meteorological variables were made with a 
range of sensors as standard. Finally, estimates of the surface wind stress were 
obtained by the inertial dissipation method using high frequency wind speed 
measurements made with a Research R2A sonic anemometer. 

6.2	Sensors Deployed

Meteorological variables 
Measurements from a combination of sensors mounted for this cruise alone and the 
standard RVS sensor suite were made during the cruise.  Information from a total 
of 19 sensors giving the wind speed and direction, air and sea surface 
temperatures, atmospheric humidity and pressure, downwelling radiative fluxes 
and various component temperatures for one of the pyrgeometers was logged using 
the GrhoMet instrumentation system, details of these sensors are given in Table 
6.1 and their deployment positions are shown schematically on Figure 6.1*. Prior 
to D232, modifications were made to the RVS sensor system such that data from 
the standard meteorological sensors is now recorded via the RVS Surfmet 
system which outputs data every 30 sec to the Level 'B' and every 5 sec via an 
RS232 serial link to the GrhoMet PC. GrhoMet separately acquires data from the 
cruise specific sensors at a 5 sec sampling rate from a new Rhopoint box mounted 
on the starboard rail of the foremast platform.  The two data streams are merged 
by the GrhoMet PC every 5 sec and written to the level B. 

Cloud observations
Observations of the total cloud amount and of the type and amount of low, medium 
and high altitude cloud were made at hourly intervals during daylight and 
typically three hourly intervals at night throughout the cruise using the Met. 
Office 'Cloud Types for Observers' guide as a reference. Over 600 observations 
were made in total covering a wide variety of cloud

Table 6.1 Variables and sensors logged by the GrhoMet system.

Variable		Position		Instrument		Note
----------------------------------------------------------------------------
Wet and Dry Bulb	STBD side of foremast	Psychrometer HS 1019	(1)
[psy 1dry  psy 1wet]	platform (aft sensor)	(SOC)	
Wet and Dry Bulb	STBD side of foremast	Psychrometer IO2003
[psy 2dry  psy 2wet]	platform (fwd sensor)	(SOC)	
Air temp [airtemp 1]	STBD side of foremast	Vector Inst. 203/16924
			platform
Air temp [airtemp 2]	PORT side of foremast	Vaisala HMP44L
			platform		S5040001 (RVS)	
Longwave [1wave2]	Top of foremast (port	Eppley PIR 27960	
			sensor)			(SOC)
Pyrgeometer thermopile	Top of foremast		Eppley PIR 31170
voltage [e]		(starboard sensor)	(SOC)	
Pyrgeometer dome	Top of foremast		Eppley PIR 31170
temperature [td]	(starboard sensor)	(SOC)	
Pyrgeometer body	Top of foremast		Eppley PIR 31170
temperature [ts]	(starboard sensor)	(SOC)	
Shortwave [swavep]	Gimbal mounted on port	Kipp & Zonen CM6B 
			side of foremast	962276 (RVS)
			platform
Shortwave [swaves]	Gimbal mounted stbd	Kipp & Zonen CM6B 
			side of foremast	962301 (RVS)	
			platform
Wind Speed & Directions	PORT side of foremast	Windmaster sonic
[wspeed1 wdir 1]	platform on vertical	No. 126 (SOC)	
			pole
Wind Speed [wspeed2]	PORT side of foremast	Vaisala (RVS)		(2)
			platform on horizontal 
			pole projecting forward	
Wind Direction [wdir2]	PORT side of foremast	Vaisala (RVS)		(2)
			platform on horizontal 
			pole projecting forward	
SST [sst]		Trailing from 6 m	Trailing Thermistor
			scaffold pole off port	SOAP pdm004/53
			Bow			(SOC)	

Pressure [press]	Lab			Vaisala PTB 100a
						R0450005 (RVS)

The variable names in the data files are shown [thus].  (RVS) indicates that the 
sensor is part of the standard ship's system; (SOC) that the instrument was 
added for the cruise.

Notes	(1). Dry bulb reading noisy for significant fraction of cruise
	(2). Wind speed persistently biased low by 10 - 15%

Figure 6.1*.	Plan view of the bow of the ship showing meteorological sensor 
		positions for Discovery Cruise D233. 

conditions, the resulting dataset will be used for an investigation of how the 
downwelling longwave flux may best be parameterised in terms of the cloud cover 
and other variables. 

Wind stress 
High frequency wind speed measurements were made with a Gill Instruments Solent 
Sonic Anemometer ( R2 Asymmetric Model, serial no. 37) which was mounted on the 
starboard side of the foremast platform. The anemometer was operated in Mode 1 
and the 21 Hz sampled data were logged using a PC system situated in the Plot 
that was also used for the GrhoMet output. Two programs were used to sample the 
data, standard sonic and Gill sonic the latter being a new program which 
provides additional parameters during the data processing cycle. In each case 
wind speed spectra and spectral levels are determined from the raw data. 
Standard sonic has a 10 minute sampling period starting each quarter hour. It 
derives a single PSD value in the range 2 - 4 Hz from the average of 12 data 
sections, each of which contains 1024 data points, taken within the sampling 
period. Gill sonic calculates PSD values in the sub-ranges 2 - 3 Hz, 3 - 4 Hz, 4 
- 5 Hz and 5 - 6 Hz from each section. It was initially run with an 8 minute 
sampling period which was increased to 10 minutes on JD 142 to allow comparisons 
to be made with the standard sonic program. 

6.3	Sensor Performance

Air temperature and humidity 
Dry bulb air temperature measurements were obtained from the two psychrometers, 
the vector sensor and the RVS humidity sensor. An initial problem with the 
direction of the fan supply to the psychrometers led to them being biased high 
relative to the vector sensor by of order 0.5 °C for the first four days of the 
cruise. The fan supply was reversed on JD 118 and agreement between the three 
sensors to typically within 0.1 °C was subsequently obtained with the 
exceptions due to noise noted below. The signal from the aft dry bulb sensor 
became increasingly noisy from JD 132 to 135, at which point the foremast 
connections were checked and sprayed with moisture repellent. No obvious 
problems were found but following the checks no further noise problems occurred 
until JD 138 and intermittently thereafter. The RVS sensor had an offset of 
about -0.4 °C with respect to the vector and the psychrometer values after the 
fan problem was corrected. Regarding the wet bulb temperatures, the aft 
psychrometer showed a positive bias, increasing with the amount of downwelling 
shortwave, of up to 0.2 °C with respect to the foreward sensor.  Its cause 
remains uncertain ; there was no obvious effect of shortwave on the relative 
values of the psychrometer dry bulb measurements. Given the noise in the aft dry 
bulb values and the apparent bias in the wet bulb we suggest that the foreward 
sensor values be used in any subsequent analysis. 

Radiative Fluxes-Longwave 
Measurements of the downwelling longwave flux were obtained with two Eppley 
pyrgeometers mounted on top of the foremast. The first radiometer, No 27960, was 
operated in standard mode with output according to the manufacturers 
calibration; the second, No 31170, was fitted with a circuit, supplied by Dave 
Hosom of Woods Hole Oceanographic Institute, which allowed the dome and sensor 
temperatures and the thermopile voltage to be recorded. Given these parameters 
and pre-cruise laboratory calibrations for the effect of the dome-sensor 
temperature difference and shortwave leakage on the measured longwave flux a 
corrected longwave field was produced for 31170. The dome-sensor temperature 
difference was found to be a function of both the incident shortwave and the 
relative wind speed, typical values being 1.8 °K and 1.2 °K for a shortwave flux 
Of 1000 Wm^-2 and relative wind speeds of 3 and 10 ms^-1 respectively. The 
magnitude of the required correction to the measured longwave for this effect 
was of order 10 Wm^-2. In post-cruise analysis we plan to develop an empirical 
correction for the dome-sensor temperature difference and assess the level of 
agreement of the longwave flux measured by the two instruments once it has been 
applied to 27960. A paper is being prepared on the results of the longwave study 
(Pascal and Josey, 1998). 

Radiative Fluxes -Shortwave 
Measurements of the shortwave flux were obtained with two RVS solarimeters 
mounted on the port and starboard sides of the foremast platform. Shadowing 
proved a problem as on previous cruises but in periods when the two sensors were 
clearly illuminated they were in good agreement e.g. to within 5 Wm^-2 for a 
downwelling flux of order 800 Wm^-2 on JD 122. At night, both sensors were 
typically within 2 Wm^-2 of zero. 

Wind Speed and Wind Stress 
Wind speed measurements were made with two Solent Sonic anemometers (one 
Research R2A; one Windmaster) and an RVS cup anemometer. The RVS sensor 
was mounted on a pole projecting forward from the port side of the foremast 
platform with several other instruments in close proximity. The wind speeds that 
it recorded were typically biased low by 10- 15 % relative to those measured by 
the Windmaster Sonic. The Windmaster and Research Sonics agreed in the mean to 
within 0.2 in s^-1 giving mean wind speeds of 8.03 and 8.20 in s^-1 respectively. 

Output from the two sonic programs was compared for the period JD 1421445 - 
1460915. Relative to the standard sonic output, Gill sonic gave mean wind speed 
values that were typically lower by 0.8% and PSD values higher by 5%. Generally 
both systems agreed well although the standard system was more prone to wayward 
data points particularly at low wind speeds; this being primarily due to 
vibration peaks in the spectrum affecting data in the 4 Hz region. 

Preliminary determinations of the wind stress were carried out with the standard 
sonic output using only data obtained within 30° of the bow in order to avoid 
biases in the measured speeds arising from flow distortion by the ship. The 
following least squares fit (equation 6. 1) to the variation of the neutral drag 
coefficient with 10 in wind speed was found for wind speeds > 6 m s^-1, 

	10^3 C(dn) = 0. 64 + 0.045u(10n) 	(6.1)

Sea Surface Temperature (SST). 
Measurements of the bulk sea surface temperature were made with a trailing 
thermistor (soap) and the thermosalinograph (TSG). In addition the skin 
temperature was measured with the Scanning Infrared SST Radiometer (SISTeR) 
deployed by Tom Sheasby from the University of Leicester. The SISTeR 
measurements are covered in a separate section ; comparisons of all three 
sensors carried out as part of the SISTeR study showed that there was an 
intermittent slowly decaying offset in the SST as measured by the TSG remote 
sensor. The sensor was replaced on JD 134 at 1440 but the offset problem 
continued for the remainder of the cruise. 

6.4.	Summary of Measurements

A wide variety of atmospheric conditions were sampled as the cruise track took 
the ship from the tropics to the sub-Arctic. Summary time series for each of the 
measured variables are shown on Figure 6.2*. During the first two weeks of the 
cruise, Trade wind conditions dominated with a steady flow of relatively warm, 
dry air from the North-East at typical speeds of 7-11 m s^-1. The winds slackened 
and veered to the south-west on JD 127 with the ship at latitude 38 °N. Several 
calm days followed, prior to the strongest winds of the cruise, in the range 18-
20 m s^-1 on JD 130, caused by a low pressure system to the west of Portugal. A 
high pressure system centred on the UK ensured relatively calm conditions for 
the remainder of the leg to Iceland with increasing cloud cover and relative 
humidities. Along the section from Cape Verde to Iceland the air temperature 
dropped from 22 °C to 7.5 °C and the specific humidity ranged from 13.5 gkg^-1 to 
.5 gkg^-1. The winds increased again and shifted to the Northeast during the 
Rockall Section and survey of the Rockall Trough as a low pressure system 
developed over Scandinavia. 

6.5	References

Pascal, R. W. and S. A. Josey (1998). Accurate radiometric measurement of the 
  atmospheric longwave flux at the sea surface, J. Atmos. Oceanic Technol., in 
  preparation. 

Simon Josey and Robin Pascal


Figure 6.2*.	Summary plot of meteorological conditions experienced during 
		the cruise. Time series show three hourly mean values of wind speed 
		(speed), wind direction - from - (dirn), sea surface temperature 
		(sst), atmospheric pressure (press), dry bulb temperature (psy2dry), 
		specific humidity (QAIR), relative humidity (RH), downwelling 
		longwave (Iwave1c) and downwelling shortwave (maxswvps). 

7	SALINITY MEASUREMENTS

7.1	Salinity sampling

Salinity samples were drawn from each Niskin bottle plus a duplicate each from 
Niskins 1 and 5. The only exception to this was on the very shallow casts, where 
only one duplicate was taken (from bottle 1). Sample bottles used were the 
standard 200 ml glass bottles with disposable plastic inserts and screw caps. 

7.2	Measurement

Two salinometers were installed in the constant temperature laboratory, 
(Guildline models 8400 and 8400A), but only the 8400A unit was used; the 8400 
being carried as a backup. The salinometer tank temperature was set at 21 °C but 
to maintain a laboratory temperature of 20 °C degrees, the laboratory air 
conditioning unit was set at 19 °C. 

The salinometer was standardised at the start of each crate of samples using 
batch P133 standard seawater (production date Nov '97) and salinity was 
calculated from the Guildline ratio using Microsoft Excel spreadsheet macros. 
Only 2 ampoules were found to be high in salinity, which was probably caused by 
imperfect sealing, allowing evaporation. Comparison of the CTD/bottle sample 
salinities showed that differences were better than 0.001. 

The salinometer generally performed very well, except on 2 separate occasions 
when a reading was being taken the ratio display started counting down at 
approximately 0.00001 per second, and had dropped 0.00250 after 4 minutes. After 
the cell had been flushed and refilled, the display behaved normally and gave 
expected readings. No obvious reason could be found for this. 

The only other problem encountered, was that the outlet tubing on the 
peristaltic pump came off on 2 occasions. In the first instance it was 
pushed back on to the outlet nipple, but it came off again after about 12 hours. 
This time the pump unit was replaced with the one fitted to the other 
salinometer. However this unit suddenly made the salinity readings go high. It 
was then noticed that the pump outlet tubing on this unit had cable ties fitted 
for extra security, but were missing from the original unit. The original pump 
was fined back on the salinometer with cable ties securing the tubes. The 
salinity readings then returned to normal and no further problems were 
experienced. It is suspected that some salt crystals may have been trapped in 
the spare pump, causing the salinity to go high when flushed through the cell. 

Rob Boner, Steve Alderman, Dave Jolly, Chris Wilson

8	OXYGEN MEASUREMENTS

8.1	Sampling

Dissolved oxygen samples were drawn from each of the Niskin bottles following 
the collection of samples for CFC/halocarbon analysis. Between one and four 
duplicate samples were taken on each cast, from the deepest bottles. The samples 
were drawn through short pieces of silicon tubing into clear, precalibrated, 
wide necked glass bottles and were fixed immediately on deck with manganese 
chloride and alkaline iodide dispensed using precise repeat Anachem bottle top 
dispensers. Samples were shaken on deck for approximately half a minute, and if 
any bubbles were detected in the samples at this point, then a new sample was 
drawn. The samples were transferred to the constant temperature (CT) laboratory, 
and then shaken again thirty minutes after sampling and stored under water until 
analysed. 

The temperature of the water in the Niskin bottles was measured using a hand 
held electronic thermometer probe. The temperature was used to calculate any 
temperature dependent changes in the sample bottle volumes. 

8.2	Analysis

Samples were analysed in the constant temperature laboratory starting two hours 
after the collection of samples. The samples were acidified immediately prior to 
titration and stirred using a magnetic stirrer bar set at a constant spin. The 
Winkler whole bottle titration method with amperometric endpoint detection 
(Culberson 1987) was used with equipment supplied by Metrohm. The spin on the 
stir bar was occasionally disturbed by the movement of the ship and also by the 
uneven bases of the glass bottles, leading to less ineffective stirring of the 
sample and a longer titration time. This probably did not effect the accuracy of 
the endpoint detection. The Anachem dispensers were washed out with deionised 
water, each time the reagents were topped up, to avoid any problems caused by 
the corrosive nature of the reagent. 

The normality of the thiosulphate titrant was checked against an in-house 
potassium iodate standard of 0.01 N at 20 °C at the beginning of each analytical 
run and incorporated into the calculations. A total of seven standards were used 
throughout the duration of the cruise. Blank measurements were also determined 
at the start of each run to account for the introduction of oxygen with the 
reagents and impurities in the manganese chloride, as described in the WOCE 
Manual of Operations and Methods (Culberson 1991). Thiosulphate standardisation 
was carried out by adding the iodate after the other reagents and following on 
directly from the blank measurements in the same flask, as on the cruises D227 
and D230. The thiosulphate precision was consistent throughout the cruise for 
each batch used. Tests were also carried out on each batch of alkaline iodide 
used, since some variability had been apparent on previous cruises when the 
iodide batch was changed. 

The number of pairs of duplicate measurements taken during the cruise was 461. 
Duplicate differences > 1.0 µmol l^-1 accounted for 28.2% of these duplicate 
pairs and ignoring these high duplicate differences the mean (±SD) duplicate 
difference was 0.457 (± 0.282). The duplicate difference achieved was not 
related to any of the individual calibrated bottles and high duplicate 
differences seemed to occur at random. 

8.3	Problems

Persistent bubbles in the tubing of the thiosulphate Titrino unit resulted in 
the replacement of some of the tubing at station 13480. The plastic dispenser 
was also replaced at station 13496. This seemed to solve the problem and the 
unit remained free of bubbles until the end of the cruise. 

8.4	Acknowledgement

We would like to thank Russell Davidson, Simon Josey and Chris Wilson for their 
help in taking samples from the Niskin bottles. 

8.5	References

Culberson, C. H. and S. Huang, 1987: Automated amperometric oxygen titration. 
  Deep-Sea Research 34 875-880.
Culberson, C.H., 1991: WOCE Operations Manual (WHP Operations and Methods). WHPO 
  91/1 Woods Hole. 15pp
Elizabeth Rourke, Kate Day, Tom Sheasby. 

9	NUTRIENT MEASUREMENTS

9.1	Sampling Procedures

Samples for the analysis of dissolved inorganic nutrients: dissolved silicon 
(also referred to as silicate and reported as SiO3), nitrate and nitrite 
(referred to as nitrate or N02+NO3) and phosphate(P04),were collected after 
CFCs, oxygen, and C02 samples had been taken. All samples were collected into 30 
ml "diluvial" sample cups, rinsed 3 times with sample before filling. These were 
then stored in a refrigerator (at 4 °C until analysed (between 1 and 12 hours 
after collection). 

A total of 139 casts were sampled for nutrients during the cruise. Samples were 
transferred into individual 8 ml samples cups, mounted onto the sampler 
turntable and analysed in sequence. The nutrient analysis was performed using 
the SOC Chemlab AAII type AutoAnalyser coupled to a Digital-Analysis Microstream 
data capture and reduction system. The majority of sample was analysed in 
duplicate to ensure accuracy and increase precision. 

9.2	Calibration

The primary calibration standards for dissolved silicon, nitrate and phosphate 
were prepared from sodium hexaflurosilicate, potassium nitrate, and potassium 
dihydrogen phosphate, respectively. These salts were dried at 110 °C for 2 
hours, cooled and stored in a dessicator, then accurately weighed to 4 decimal 
places prior to the cruise. The exact weight was recorded aiming for nominal 
weight of 0.960 g, 0.510 g and 0.681 g for dissolved silicon, nitrate and 
phosphate respectively. When diluted using MQ water, in calibrated 500 ml. glass 
(or polyethylene for silicate) volumetric flasks these produced 10 mmol l^-1 
standard stock solutions. These were stored in the refrigerator to reduce 
deterioration of the solutions. Two standard stock solutions were required for 
each nutrient over the duration of the cruise, checked daily against OSI 
standards as described later. 

Mixed working standards were made up once per day in 100 ml calibrated 
polyethylene volumetric flasks in artificial seawater (@40g l^-1NaCl). The 
working standard concentrations, corrected for the weight of dried standard salt 
and calibrations of the 500 ml and 100 ml volumetric flasks are 
shown in Table 9. 1. 

A set of working standards was run in duplicate on each analytical run to 
calibrate the analysis. The top standard was also run in duplicate at the start 
of each analytical run as it had been shown to increase the linearity of the 
standardisation (Holley, 1998). 

Table 9.1 Working nutrient standard concentrations

Standard	Silicate (µmol l^-1)	Nitrate (µmol l^-1)	Phosphate (µmol l^-1)
-------------------------------------------------------------------------------------
		415-448	449-553		415-448	449-553		415-448	449-553
S1		40.112	40.168		40.148	40.148		2.006	2.007
S2		30.129	30.171		30.156	30.156		1.507	1.508
S3		20.028	20.056		20.046	20.046		1.001	1.002
S4		10.006	10.020		10.015	10.015		0.500	0.501


9.2	Analysis

Silicon
Dissolved silicon analysis followed the standard AAII molybdate-ascorbic acid 
method with the addition of a 37 °C heating bath (Hydes, 1984). The colorimeter 
was fitted with a 50 mm. flow cell and a 660 nm filter. The gain was adjusted to 
2.8 for a maximum response at 40 µmol l^-1.

Nitrate 
Nitrate (and nitrite) analysis followed the standard AAII method using 
sulphanilamide and naphtylethylenediamine-dihydrochloride with a copperised-
cadmium filled glass reduction column. A 15 mm flow cell and 540 nm filter was 
used with a gain setting of 2. 1, adjusted for concentrations of up to 40 µmol 
l^-1. Nitrite standards equivalent in concentration to the third nitrate 
standard were prepared each day to test the efficiency of the column. 

Phosphate
For phosphate analysis the standard AAII method was used (Hydes, 1984) which 
follows the method of Murphy and Riley (1962). A 50 mm flowcell and 880 mm 
filter were used and the gain set to 9 throughout the cruise, measuring 
concentrations of 0-2 µmol l^-1.

There was a large amount of noise on this channel predominantly due to two 
reasons. 

-  Firstly, the photometer was very sensitive to light 
-  Secondly, it was sensitive to movement. 

The light fitting above was removed and the entire photometer was covered with 
black sheeting, eliminating this problem. However when the ship rolled in rough 
weather the phosphate baseline noticeably shifted back and forth with the ship's 
roll. This resulted in an increase in error of peaks and is a problem that needs 
to be addressed for future cruises. It is of note that the photometer had not 
been safety tested since 9th August, 1996. 

9.3	Operation and maintenance

Reagents for each of the nutrients analysed were made up as and when required 
from pre-weighed salts; some maintenance was also required. Position 38 on the 
rotating table occasionally was not sampled. This was temporarily eliminated by 
keeping the autostop switch off. The tubing on the peristaltic pump was fully 
replaced once a week throughout the cruise and all tubing was rinsed with dilute 
Decon solution. In addition the chart recorder had some loose connections 
(corresponding to the nitrate channel) which caused problems. This unit had also 
not been safety tested since 9th August, 1996. 

9.4	Precision - Duplicate and quality control measurements

Samples were analysed in duplicate except for occasions where time was limited 
either due to problems (described above) or to large quantity of samples being 
collected. 

Several quality control samples were also analysed on each run. Two quality 
control samples were made up from standard solutions supplied by OSI 
(prepared each day in plastic volumetric flasks using NaCl solution). The 
concentrations were adjusted to be equivalent to the 2nd and 4th working 
standard concentrations (so the QC material is referred to as QC2 and QC4 
respectively). In addition a deep water sample was collected from the test 
station at ~ 3500 in. The deep water QC samples were decanted into clean rinsed 
plastic diluvial containers and stored in the cold store until required, using I 
per analytical run. Each QC sample was analysed in duplicate (except for where 
time was limited as described above), variations in the results are shown in 
Figures 9.1* - 9.3* (colours, indicate duplicates) 

9.5	References

Holley, S.E., 1988. Report on the maintenance of precision and accuracy of 
  measurements of dissolved inorganic nutrients and dissolved oxygen over 43 
  days of measurements on Cruise 230 'FOUREX' (07 Aug - 19 Sep 1997). SOC 
  Internal Document No 30, 34 pp.
Hydes, D.J., 1984. A manual of methods for the continuous flow determination of 
  nutrients in seawater. IOSDL Report 177, 40pp.
Murphy, J. and J.P. Riley, 1954. A modified single solution method for the 
  determination of phosphate in natural waters. Anal Chem. Acta, 27 31-66.

Virginie Hart

10	HALOCARBONS MEASUREMENTS (inc CFC TRACERS)

There were two main aims to the halocarbon work on D233: 

-  the first was to collect a comprehensive CFC tracer data set to WOCE 
   standards for CFC-11, CFC-12, CFC-113 and carbon tetrachloride in order to 
   characterise the water masses of the region and make a study of their spreading, 
   mixing and ventilation rates. Particular emphasis was placed on Labrador Sea 
   Water, Mediterranean Water, waters of Southern Ocean origin (Antarctic 
   Intermediate Water and Antarctic Bottom Water) and the 
   circulation/recirculation patterns waters prevalent in the Rockall Trough. 

Figure 9.1*	Silicate QC Deep, QC2 and QC4.

Figure 9.2*	Nitrate QC Deep, QC2 and QC4.

Figure 9.3	Phosphate QC Deep, QC2 and QC4.

-  The second was to make measurements of as many halogenated compounds as 
   practically possible in order to access the oceanic source/sink of compounds 
   such as methyl bromide, methyl iodide, methyl chloride, methylene chloride, 
   bromochloromethane and the anthropogenic CFC replacements (sink only). 

10.1	Sample Collection

Samples were drawn from 10 1 Niskin bottles which had been checked for physical 
integrity and chemical cleanliness prior to the cruise; no contamination 
problems developed during the cruise. Samples were drawn first from the rosette, 
directly into 100 ml ground glass syringes and stored under a continuous 
flushing stream of surface seawater to keep gas tight. Occasionally 250 ml 
ground glass syringes were used to provide a larger sample for GC-MS analysis. 
Most samples were analysed within 12 hours of collection although the frequency 
of CTD stations sometimes led to a further delay of up to 12 hours, however 
there was no evidence of sample degradation when this occurred. 

10.2	Analysis

Halocarbon analyses were carried out using a modified version of the GC-ECD 
system described in Boswell and Smythe-Wright (1996), with the same 
modifications as specified in Bacon (1998) for RRS Discovery cruise D230. The 
chromatography run time ranged from 38-41 minutes depending on the carrier gas 
flow. This enabled 16 compounds to be measured (up to and including carbon 
tetrachloride) after which time the chromogratographic run was terminated in 
order to achieve a balance between number of compounds measured and sample 
throughput. Measurements were made on 124 out of a total of 139 stations, 
approximately half to full depth and half to 200 m (to focus entirely on 
biogenic gases). Occasionally, were station frequency reduced the number of 
samples that could logistically be handled, it was necessary to focus on 
analysing samples taken from bottle depths which corresponded to bottom to mid 
waters to achieve the CFC tracer aims of the cruise. 

10.3	Problems

The main problem occurred on JD 132 during the analysis of samples from station 
13468 when the joint connecting the 'B' trap to the extraction board became 
loose allowing water to pass into the precolumn. Despite immediately action, 
water percolated through the column to the detector causing irreparable damage 
which resulted in the entire 'B' channel (column, precolumn and detector) being 
replaced. Because of the water ingress three valves later became blocked and had 
to be cleared. As a result of these problems some stations were incompletely 
analysed. 

10.4	GC-MS

When time permitted a newly purchased HP GC-MS system was used to analyse 
surface samples. This new system had been set up in the laboratory prior to the 
cruise using gas samples but had not been previously tested for seawater. First 
results with regard to achieving the detection limits of the GC-ECD system were 
very encouraging, but due to pressure on personnel the system was not used 
routinely for the analysis of samples. It did however prove very useful in 
identifying a number of peaks observed with the GC-ECD system. (Further fine 
tuning of the GC-MS methodology since the cruise has resulted in the system 
being adopted for future work at sea). 

10.5	Automated GC-MS trials

A fully automated GC-MS system for continuous sea water measurement was tested 
during the cruise but due to pressure of other work and problems with the 
control software only limited success was achieved with its operation and no 
data collected. 

10.6	Calibration and Precision

CFC tracers were calibrated using a 20 point calibration from a gas standard 
prepared by the NOAA CMDL laboratory which had been cross calibrated to the SIO 
1993 scale. Biogenic gases were calibrated using similar techniques but with 
gases supplied by a Kintek gas standards generator. Duplicate measurements were 
made at a number of stations and showed precision and accuracy of CFC tracers to 
be within WOCE requirements: less than I% or +0.005 pmol kg^-1 for CFC-11 and 
CFC-12 at low levels. 

10.7	Acknowledgements

We would like to thank Russell Davidson, Ben Schazmann and Alex Megann for their 
much appreciated help with the collection of CFC samples. 

10.8	References

Bacon S, 1998. RRS Discovery Cruise 230, 7 August - 17 September 1997. Two 
hydrographic sections across the boundaries of the subpolar gyre:  FOUREX.  
Southampton Oceanography Centre Cruise Report No 16, 104 pp.
Boswell, S.M. and Smythe-Wright, D. 1996. Dual-detector system for the shipboard 
analysis of halocarbons in sea-water and air for oceanographic tracer studies. 
Analyst, 121: 505-509. 

Cristina Peckett, Iris Soler-Aristigui, Claudia Dimmer, Denise Smythe-Wright

11	CARBON DIOXIDE MEASUREMENTS

The aim of the CO2 work was to make full depth measurements of pH, and 
alkalinity in order to calculate the total inorganic carbon present in the 
ocean at the time of the cruise and to make underway measurements of the partial 
pressure of CO2 (PCO2) in surface seawater from the ship's non-toxic supply and 
air. Such studies are becoming increasingly important in detecting the changes 
in the carbonate system in the oceans as a result of the increases of CO2 in the 
atmosphere due to the burning of fossil fuels. The components of the carbonate 
system: pH, alkalinity, partial pressure of CO2 (PCO2) and total inorganic 
carbon are interrelated by the thermodynamics of the carbonate system in 
seawater and the buffers used to determine the pH. By measuring two of these 
variables it is possible to calculate the other two by means of a set of 
equations deduced from thermodynamic equilibrium. During the CHAOS cruise, 
samples were collected at every second station, and analysed for pH and 
alkalinity; PCO2 calculated from this data was compared with the continuous 
surface measurements from the non-toxic supply. In addition, the continuous 
measurements of PCO2 in air and surface sea samples were combined to estimate 
the CO2 gradient across the sea surface and together with the wind speed, piston 
velocity and solubility of CO2 used to calculate the CO2 flux between ocean and 
atmosphere. 

11.1	pH measurements

Sample Collection

pH samples were collected directly into 100 ml glass bottles which were kept in 
the dark until analysed. A total of 62 stations were sampled following behind 
the collection of CFC/halocarbons and oxygen samples.

Analysis

pH measurements were made using a triple-wavelength spectrophotometric technique 
(Byrne, 1987). This required measuring the sample adsorption after the dye-
solution addition, at the acid indicator species wavelength (434 nm), at the 
basic indicator species wavelength (578 nm) and at a wavelength with no 
adsorption from any of the two referred species (730 nm) to correct the base 
line. The indicator used was Aldrich m-cresol purple sodium salt (C21H17O5Na) 
prepared in seawater to avoid changes in the sample salinity. Prior to analysis
all samples were stabilised in a thermostatic bath to 25 °C; this sample 
temperature was monitored with a platinum resistance Pt-probe. The samples were 
then individually pumped into the flow cell of a Hewlett-Packard -array 
spectrophotometer via a mixing channel; the temperature of the cell holder being 
controlled by a Peltier system to 25 °C. A blank reading was taken before the 
indicator solution was added to the mixing channel and the two solution mixed. 
During the analysis the sample flow was stopped three times and three different 
measurements of pH were made at three different indicator concentrations using 
equation 11.1 (Clayton and Byrne, 1993): 

pHt=1245.69/T+3.8275+2.11 x 10-3(35-s)+Iog[(R-0.0069) / (2.222-0.133R)] 11.1

To eliminate the pH indicator perturbation in the sample a linear fit regression 
was made to the three pH measurements to give a pH value at zero indicator 
concentration. This result is the hydrogen ion concentration in total scale. 

11.2	pC02 measurements

Sample Collection

pC02 samples were obtained continuously from a depth 2-3 m though the ship's non 
toxic seawater supply. Seawater was pumped directly into a 'debubbling' tank and 
then fed at a rate of 4 1 min^-1 to a 'shower head' type equilibrator.

Analysis

The none dried gas phase was sampled from this equilibrator and passed into an 
IR CO2/H20 analyzer model LI-6262. Simultaneously an air sample was taken and 
passed via a soda lime/Mg(ClO)2 filter to clean it of CO2 and H2O into a 
different channel of the analyser to give a zero CO2/H2O IR. spectra. The result 
is a continuous estimate of theCO2 mole fraction in the surface seawater in 
matmospheres of CO2 (when referenced to atmospheric pressure). Data from the 
ship's global position system was used to locate and date all the CO2 data.

Calibration and standardisation 

Every 60 minutes marine air was pumped from an intake mounted clear of the 
ship's superstructure to minimize the possible contamination from the ship, into 
the analyzer to obtain the CO2 mole fraction in the air. A standard of CO2 made 
up in synthetic air was also run every 6 hours to detect changes in the zero 
channel value. 

Problems 

Unfortunately severe problems with the data transmission card prevented the 
continuous logging of the data file and so it was necessary to write down 
position, time and pCO2 data every 10 minutes or less during the entire cruise. 

Luis Laglera-Baquer and Maria Somoza-Rodriguez

11.3	Alkalinity Measurements

Sample Collection 

Seawater samples for alkalinity measurement were collected from all depths at a 
total of 62 stations following behind those for CFCs, oxygen and pH. The samples 
were drawn directly into 300 ml plastic bottles and stored in the dark until 
analysed either the same day or one day later. 

Analysis

Alkalinity was measured using an automatic potentiometric Titrino Metrohm, 
titrator fitted with a Metrohm Combination glass electrode. Potentiometric 
titrations were carried out with hydrochloric acid to a final pH of 4.44 (Perez 
and Fraga, 1987b). The hydrochloric acid was made up from an ampoule of Fixanal 
HCL to give a molarity of 0.5 M when dissolved in 5 1 of milli-Q water (the 
exact molarity was established later in the laboratory).

The electrodes were standardised with three buffers according to the following 
sequence: 

i   calibration of the combined electrode with NBS buffers of pH 7.413;
ii  checking of the electrode response with a pH 4.008 NBS buffer solution
iii adaptation of the electrode to the strong ionic strength of seawater by 
    means of a pH 4.4 seawater buffer containing 4.0846 g of C2H5KO4 and 1.52568 
    g of B4O7Na2H2O in 1 Kg of CO2 - free seawater. 

At each station, samples of CO2 reference material for oceanic measurements, 
batch 42 (CRM) and of a seawater substandard (SSS) and were analysed at the 
beginning and end of each series of samples. The SSS is a quasy-steady surface 
de-aerated 25 1 seawater sample taken from the non-toxic supply and stored in 
the dark. The variations in the measured SSS and CRM alkalinity during the 
cruise will be used to correct the electrode deviations over time and so refer 
the alkalinity results to the same line base. All concentrations are calculated 
in mmol kg^-1 

Iris S. Aristegui and Maria J. R. Somoza. 

11.4	References 

Byrne R. H., 1987. Standardization of standard buffers by visible spectrometry. 
  Analytical Chemistry 59, 1479-1481.
Clayton, T. D. and R. H. Byrne, 1993. Spectophotometric seawater pH 
  measurements: total hydrogen ion concentration scale concentration scale 
  calibration of m-cresol purple and at-sea results. Deep-Sea Res. 40, 2115-2129
Perez F. F. and F. Fraga, 1987a. The pH measurements in seawater on NBS scale. 
  Marine Chemistry 21, 315-327.
Perez F. F. and F. Fraga, 1987b. A precise and rapid analytical procedure for 
  alkalinity determination. Marine Chemistry 21, 315-327.

12	PHYTOPLANKTON AND PIGMENT STUDIES

There is some evidence to suggest that phytoplankton are natural producers of 
halocarbons which are involved in ozone depletion. The work carried on the 
cruise forms part of the SOC SASHES project, investigating the sources and sinks 
of halogenated environmental substances and was carried out to compliment the 
seawater and atmospheric halocarbon studies. The primary aim was to collect 
biological samples during the spring phytoplankton bloom period for algal 
pigment and speciation studies back at SOC and to make shipboard measurements of 
chlorophyll. 

12.1	Pigment studies

Sample collection

Chlorophyll and HPLC sampling focused on the surface layer with the top 6 Niskin 
bottles from the CTD (usually fired at around 120,75, 50, 25, 10 and 5 m) being 
sampled at 117 stations. Samples were collected in 5 1 carboys which were rinsed 
in the sample prior to being filled.

For HPLC analysis, water samples (2 1) and duplicates were filtered through 25 
mm Whatman GF/F filters using a specially developed positive pressure filtration 
unit TOPPFUN. The filter papers were immediately placed in cryovials and stored 
in liquid nitrogen for subsequent HPLC algal pigment analysis at SOC. 

For chlorophyll analysis, two 100 ml aliquots were filtered through 25 mm. 
Whatman GF/F filters at low pressure. The papers were then placed in glass vials 
containing 10 ml of 90% acetone and immediately stored in the dark at -5 °C for 
24 hr in order to extract the chlorophyll. 

Chlorophyll analysis 

Samples were warmed to room temperature before the fluorescence was measured 
using a Turner Designs Fluorometer. To measure the phaeopigments in the sample, 
4 drops of 10% hydrochloric acid were added and the fluorescence remeasured. 
Chlorophyll standard solutions (Sigma) covering the expected range of samples 
were used for calibration of the fluorometer and were made up and measured along 
with blanks for each set of samples. Throughout the cruise three primary 
standards were used to make up the calibration standards. The chlorophyll 
concentration of these were calculated from the absorbance measured before and 
after acidification at 665 nm. and 750 nm in a Camspec UV-visible 
spectrophotometer.  Chlorophyll and phaeopigment concentrations were calculated 
using equations from the JGOFS protocols (1994) in Microsoft Excel. 

Chlorophyll concentrations ranged from 0.001 to 8.72 mg m-3; the highest 
concentrations being found in the sub-polar gyre, around the Iceland 
coast where there was evidence of the spring bloom taking place. High 
concentrations were also seen off the coast of Africa due to the upwelling 
event. The chlorophyll maximum shifted from around 50 to 100 m in the 
subtropical gyre to between the surface and 20 m in the sub-polar gyre. 

Problems

The main area of inaccuracy was due to filtering leakages on the filtering 
bottles and this problem will be addressed at SOC.

12.3	Phytoplankton studies

Sample collection 
Phytoplankton samples for microscope speciation studies at SOC were taken at the 
surface, the chlorophyll maximum and a sample in between these two depths. Two 
100 ml amber glass bottles were filled for each depth and preservative agents 
(Lugol's iodine and Formalin) added to each. In addition, samples were collected 
at these depths and also at around 90 m for picoplankton identification and 
enumeration. A total of 702 phytoplankton and 468 picoplankton samples were 
taken from 117 stations. 

Russell Davidson and Ben Schazmann

12.4	Culture Studies

Previous work has shown that phytoplankton species differ in the halocarbons 
they produce, and indeed many do not seem to give off any volatile halogenated 
compounds at all. The aim this work was to isolate the most common species of 
phytoplankton in the surface waters when concentrations of either chlorophyll 
and/or halocarbons such as methyl bromide, methyl iodide and methyl chloride 
were high, with the assumption that it is those species that are primarily 
responsible for the high halocarbon levels seen. These species will subsequently 
be grown and cultured back in the lab at SOC in a specially adapted gas-tight 
culture flask and the headspace gas sampled and analysed for halocarbons using 
the GC-ECD. 

Sample collection Surface water samples of approximately 15 1 were collected 
whilst on station using the bucketover-the-side method and filtered through a 20 
µm nylon mesh to concentrate the phytoplankton into a smaller volume of water. 
At a few stations seawater from the chlorophyll maximum was collected by firing 
an extra bottle on the CTD rosette. Small sterile Petri dishes of seawater were 
examined under a Zeiss compound microscope at x 100 and individual cells of the 
most prolific species picked up into sterile capillary pipettes (pulled from 
Pasteur pipettes using a Bunsen flame). Cells were isolated into sterile 
polyethylene tubes containing 1 ml artificial seawater media and placed in a 
Mercia Scientific illuminated incubator at 15 °C on a 16 hour light: 8 hour dark 
cycle. Filtered seawater was used in later isolations. 

Due to time constraints for this work only stations occupied in the late 
afternoon could be sampled. Water samples were taken from 34 stations and 
isolates collected from 14 of them, with a total of 122 isolates taken. 

Cristina Peckett

12.5	References

JGOFS, 1994. Protocols for the JGOFS. Intergovernmental Oceanographic Commission 
  Manual and Guides 29 170 pp

13	DISSOLVED ORGANIC NITROGEN

Samples were collected along the 20 °W section for dissolved organic nitrogen 
measurement on a ship of opportunity basis as part of an SOC study of dissolved 
organic nitrogen in the North Atlantic. Samples were drawn directly into 100 ml 
acid washed plastic bottles and stored frozen for subsequent analysis at SOC. 

14	ATMOSPHERIC GAS MEASUREMENTS

Production of halocarbons by the chemical industry is now restricted under terms 
laid out in the Montreal Protocol and subsequent revisions. Controlled 
substances include CFCs, halons, carbon tetrachloride, methyl chloroform, HCFCs, 
HBFCs and methyl bromide. Long term monitoring of all such species is therefore 
important to verify the expected decrease in the atmospheric halogen burden, and 
to assess the environmental impact of the new substitute compounds. 

There are also a variety of halocarbons known to be produced biogenically, 
including methyl chloride, methyl iodide, bromoform, dibromomethane, chloroform 
and methyl bromide. These species provide a significant contribution to the 
total atmospheric halogen load and are synthesised predominantly by oceanic 
biota, fungi, or released during biomass burning. Detailed information about the 
sources, sinks, and seasonal and annual cycles for many of these naturally 
occurring halocarbons is sparse, and high frequency, high precision measurements 
are needed from a range of biospheres to quantify their global atmospheric 
budgets. 

14.1	Analysis

The fully automated instrumentation as described by Bassford (1998) consisting 
of a novel twin ECD gas chromatograph (HP 6890) with sample enriching 
Adsorption-Desorption System (ADS) (Simmonds, 1995) enabled halocarbon 
concentrations at pptv levels to be determined at hourly intervals. The effluent 
from the first electron capture detector (ECD) passes into the second ECD which 
has enhanced sensitivity due to oxygen doping of the detector make-up gas.  Such 
a unique serial detection system was designed to be extremely sensitive for 
determination of both strong and weakly electron capturing species. Strongly 
electronegative compounds efficiently attach electrons during passage through 
the first detector and produce an attenuated response in the second oxygen doped 
detector. This results in a decrease in peak width, and consequently the 
potential for an increase in resolution for other less responsive compounds.  
The procedure allows precise quantification of a suite of 27 halocarbons, 
including compounds such as CH3Cl and CH3Br, which are poorly detected by normal 
ECDs.

The system performed routine analysis of air and standard samples in a 
continuous three hour cycle (two air runs followed by a standard analysis). 

14.2	Sample collection

The air sample was obtained using a length of 1/4 copper tubing from the deck 
lab to the top of the foremast, through which air was pumped for 10 minutes 
before a 200 ml sample was taken. 

14.3	Standardisation and calibration

The bracketing of air runs by standards enabled quantification of the 
atmospheric measurements and allowed for any drift in sensitivity. The 
working standard containing halocarbons at near ambient concentrations was 
obtained from a gravimetrically prepared calibration standard containing 16 
atmospheric halocarbons present at ppm concentrations with a stated accuracy of 
standard will be compared with absolute calibration standards maintained by the 
Scripps Institute and NOAA in the USA, and the standard used to determine the 
concentration of CFCs in the water on this cruise. 

For those compounds which are known or suspected to be unstable in a gaseous 
mixture at low concentrations, such as methyl iodide, atmospheric mixing ratios 
are calculated retrospectively using C2Cl4 (PCE) as a surrogate standard. A 
liquid standard is prepared by performing a volumetric (verified 
gravimetrically) dilution of either an EPA calibration mixture (Supelco EPA 624) 
or pure components into HPLC grade heptane. The standard is then either injected 
into an evacuated 3.5 1 elecropolished stainless steel flask and pressurised to 
the required concentration using ultra high purity zero air (Air Products Ltd.), 
or injected directly on column through the purged packed injection port. 
Assuming the chromatographic peak height (H) is proportional to concentration 
(C) of an uncalibrated compound in a sample, the relationship between compound 
x andC2Cl4 (PCE) can be expressed in terms of relative response ratios (13.1 and 
13.2). 

Hsx = 	kx * Cx		H(c2cl4)= k(C2CI4) * C(C2Cl4)		13.1

	kx	   =	Hx * CC2Cl4
K     = ------		------------				13.2
	kC2Cl4		HC2CI4 * Cx

To assess system precision, each standard run was compared with standard runs 
before and after, therefore correcting for any drift in detector sensitivity. 
The standard ratio was calculated by dividing each run by the mean of its 
bracketed standards. 

14.4	Problems

Much of the deviation observed on the cruise was due to the variations in 
laboratory temperature, particularly in the tropics where the daytime lab 
temperature often reached 30 °C. As sample trapping occurs at room temperature, 
high temperatures tend to lead to a slight decrease in trapping efficiency. The 
amount of water reaching the detectors through the system also affected the 
detector sensitivity. 

The high laboratory temperature at the start of the cruise also made it 
necessary to change the GC temperature programme to a run start temperature of 
35 °C instead of 30 °C as previously used. However, the higher start temperature 
still gave satisfactory peak separation for the early eluting compounds. 

Further problems encountered with the utilisation of the instrumentation in a 
shipboard environment were mainly associated with the removal of water from the 
air sample. Initially a three stage drying system was planned, comprising an ice 
trap (which removes water through condensation), a Nafion dryer (which removes 
water through a membrane due to a counter flow of dry nitrogen) and a potassium 
carbonate drying agent trap. However, after initial standard runs through the 
system doubts were expressed about the integrity of an air or standard sample 
having passed through the drying agent. Both contamination and removal of 
halocarbons by the potassium carbonate appeared to be a problem. Thereafter, 
only the ice trap and Nafion dryer were used. The ice trap design successfully 
utilised in previous land-based field campaigns consisted of 1/16" tubing 
immersed in an ice bath, however with the volume of water collected in the 
marine environment, ice blockages became a problem with this trap and a trap 
comprising 1/4" tubing was utilised with twice daily drainage of water. The 
length of 1/4" coiled tubing had to be extended by Iceland in order to cope with 
the increased volume of water to be trapped out during foggy weather. Additional 
minor problems involved two misaligned valves which temporarily prevented air 
flow through the system, and three crashes of the HP Chemstation software which 
runs the gas chromatograph and is responsible for data collection, resulting in 
two nights without data acquisition. Frequent system leak checking was necessary 
as the motion of the ship loosened fittings particularly into valves. 

The data obtained will allow comparison with atmospheric data acquired on 
campaigns at Mace Head Atmospheric Research Station, Ireland and Ny-Ålesund, 
Spitzbergen. Concentrations monitored will be correlated with local 
meteorological data recorded on board the ship, wind trajectories, and the 
surface water halocarbon concentrations. The data will help to determine the 
extent of global tropospheric mixing of the anthropogenic halocarbons and to 
compare global source strengths of the naturally produced compounds.

14.5	References

Bassford M.R, Simmonds P.G, Nickless G, 1998. An Automated System for near-real 
  time monitoring of trace atmospheric halocarbons. Anal. Chem.70, 958-965. 
Simmonds P.G. O'Doherty SJ, Nickless G, Sturrock G.A, Swaby R, Knight P, 
  Ricketts J, Woffendin G, Smith R., 1995. Anal. Chem. 34, 717-723. 
Claudia Dimmer.

15	SISTeR INSTRUMENT

The Scanning Infra-red Sea-surface Temperature Radiometer (SISTeR) is a thermal 
infra-red radiometer designed and built by Dr. Tim Nightingale at the Rutherford 
Appleton Laboratory (RAL) in Didcot, Oxford. It weighs approximately 20 Kg and 
is roughly 30 x 30 x 60 cm.  The instrument was designed for the validation of 
the 2nd Along Track Scanning Radiometer (ATSR-2) instrument on board ERS-2. The 
infra-red filter used during the cruise is centred on 10.8 µm. The radiometer 
can be programmed to look forward at any given angles from 0° (nadir) to 180° 
(zenith), and at its two internal black-bodies.

15.1	Aims

The data collected during this cruise will be mainly used in studying the so-
called 'skin-effect' by comparing the radiometric 'skin' sea temperature with 
the 0 cm bulk sea temperature from the 'soap' instrument. This measured 'skin-
effect' and other meteorological data will then be used to test various models 
of this effect. Also using these data the effect of validating satellite 
radiometers (which measure the skin temperature) with bulk temperature will be 
investigated. A further aim is the validation of the ATSR-2 instrument by 
comparing coincident radiometric sea temperatures measured from the ship to 
those measured by the satellite. 

15.2	Instrument Deployment

The instrument was mounted on the bow of the RRS Discovery on a 10 mm. aluminium 
plate bolted on through 6 holes drilled on previous cruises. Cables were made to 
connect the instrument through the ship's loom to a laptop in the main lab using 
the junction box on the starboard side of the bow. It was mounted such that it 
was looking at an angle of 45° to starboard to avoid looking at the ship's wake 
or shadow. SISTeR was programmed to look at the sea at 30° (from nadir), then at 
three sky angles of 120°, 150° and 170° respectively. It then looked at its two 
on board black-bodies (one heated) for calibration and the measurement cycle 
repeated. 

A second mount for SISTeR was built and installed on the port side of the 
foremast, using the junction box on the starboard side of the mast. Due to the 
need to cover the instrument during bad weather, it was decided that the bow 
mount was more suitable as access to the foremast is restricted during bad 
weather. 

15.3	Preliminary Results

The instrument was deployed for most of the cruise and performed well. 
Additionally two calibration runs, using an external black-body source, were 
performed at the start and half way through the cruise, with a third planned to 
be done at the end. From the first calibration the instrument had an accuracy of 
better that 0.05 °K and a peak to peak noise of 0. 1 °K as expected (see Figure 
15 1*). 

Halfway through the cruise the accuracy was still 0.05 but the noise had 
increased to 0.2 °K peak to peak as the mirror degraded due to salt corrosion 
etc. There was one clear day coincident with an ERS-2 overpass that could result 
in a validation point and one partially cloudy day that may also yield a 
validation. 

Thomas Sheasby

Figure 15.1*	Graph showing a detail of the first SISTeR calibration. The 
		SISTeR data are the dots, the actual temperature the line. 

16	THERMOSALINOGRAPH MEASUREMENTS

Surface temperature and salinity were measured continuously throughout the 
cruise using a Falmouth Scientific Inc (FSI) shipboard thermosalinograph (TSG). 
The TSG comprises two FSI sensor modules, an Ocean Conductivity Module (OCM) and 
an Ocean Temperature Module (OTM), both fitted within the same laboratory 
housing. Sea surface temperature is measured by a second OTM situated on the 
suction side of the non-toxic supply in the forward hold. The non-toxic intake 
is 5 m below the sea surface. Data from the OCM and the OTM modules are passed 
to a PC, which imitates the traditional level A system, passing it to level B at 
30 second intervals. 

The temperature modules are installed pre-calibrated to a laboratory standard 
and laboratory calibration data are used to obtain four polynomial coefficients. 
A similar procedure is employed for the conductivity module. Salinity samples 
were drawn from the non-toxic supply at approximately four-hourly intervals for 
calibration of computed TSG salinity. These samples were then analysed on a 
Guildline 8400A salinometer in the usual way. The four hourly bottle salinities 
from the non-toxic supply are used as true salinity from which to calculate an 
offset to be applied to the TSG salinities. TSG salinity is usually calculated 
from the measured conductivity (cond) and temperature at the housing located 
in the water bottle annexe (htemp). The temperature of the surface water is 
measured by the remote or marine sensor (rtemp). 

16.1	Daily data processing

-  Acquisition of raw TSG data (htemp, rtemp, cond) from level A and conversion 
   to level C PSTAR format (executable: tsgexecO). 
-  Averaging of raw TSG data over a basis of 2 minutes and merging with 
   navigation data from the RVS Bestnav file (tsgexec 1). 

After analysis, bottle salinity data was recorded in Excel and saved as a tab-
delimited text file, which is ftp'ed from a Mac, converting the data to PSTAR 
format and time is converted to seconds (tsg.exec, tsgexec2). 

16.2	Calibration and validation

Calibration was initiated by merging the bottle file (tsg233.samples) and TSG 
file (tsg233) on time using PSTAR. The differences (bottle salinities - TSG 
salinities) were calculated and 3 outlying data points were removed from outside 
the range [-0.5, 0.5] psu. The differences were plotted against bottle salinity, 
conductivity and distance run. The most linear scatter was the plot of  
difference against bottle salinity, increasing with increasing salinity. A 
quadratic calibration was then applied to the TSG data (PEXEC : plreg2) and the 
calibrated data was compared with the bottle salinities to produce a mean 
difference to 4 decimal places of -0.0629 (s.d.=0.3770). After the removal of 
the 3 rogue data points, the new statistics were mean=0.0000 psu (s.d.=0.0310). 

It must be noted that bottle salinities after JD 144 (24th May) were not 
included in the calibration, leaving 93 bottle samples for the calibration of 
the 2 minute TSG data set. 

Thanks to Steve Alderson for his help with calibration. 

Penny Holliday and Chris Wilson

17	EXPENDABLE BATHYTHERMOGRAPH MEASUREMENTS

A total of 35 Expendable Bathythermographs (XBTs) were deployed. These were 
kindly provided by the Hydrographic Office (MoD) in Taunton on the condition 
that a copy of the data would be returned to them after the cruise for 
incorporation into their database. In 0, 36 probes were supplied, being one box 
(12 probes) of T5s (depth rated to 1830 m) and two boxes (24 probes) of T7s 
(depth rated to 780 in). It was found to be necessary to slow the ship speed to 
approximately 6 kts, to deploy the T5s, although the T7s could be deployed at 
full speed (11- 12 kts). 

One probe was deployed as a trial of the system on the preceding cruise (D232), 
and one probe failed to record to the data disk for an unknown reason. 
Consequently, 34 probes were successfully deployed (11 T5s and 23 T7s), 
representing a high degree of reliability (for example, on previous cruises it 
has often been the case that some 10% of probes have failed). The probes were 
deployed from the aft port quarter of the ship and this is therefore clearly a 
good place for such deployments, and for avoiding contacts between the wire and 
the ship's hull. The data were transferred to the RVS and PSTAR systems via 
floppy disk. Appendix B gives information on the XBT stations. 

The only problem concerned the transmission of the data to satellite via the 
GOES system. The GOES buffer became full after the first four XBT drops, and the 
system then failed to upload the data to the satellite at the synoptic hours, so 
that no more XBTs could be sent to the buffer. This problem has been encountered 
on previous cruises. Although this was investigated on the present cruise, no 
solution could be found. This will be looked at further by the technical staff 
after the ship has returned to port. 

The XBTs were deployed during the survey of the Rockall Trough area (between 53-
58 °N, 9-16 °W) and gave useful additional data to provide increased resolution 
between the CTD stations, and to fill in sections between the ends of the CTD 
lines. An example is shown in Figure 17.1*. As well as revealing the mixed layer 
structure in the upper ocean (at 55° 58'N, 10° 30'W), this figure also indicates 
the detailed nature of the data coverage obtained. The data from the 34 
successful drops will be sent to the Hydrographic Office as required. 

Adrian New

Figure 17.1*.	XBT profile from Station 13

18	PRECISION ECHOSOUNDER

The Simrad EA500 Hydrographic Echosounder was used in bottom detection mode 
throughout the cruise. Depth values were passed via an RVS Level A interface to 
the Level C system for processing, with a nominal transducer depth of 11.5 m 
used. A visual display of the return signal was displayed in the Simrad VDU. 
Hardcopy output was produced on a colour inkjet printer. The amount of cable 
submerged whilst on station was approximately 11.5 m, and while steaming the 
echosounder was 2 m shallower. So during steaming the measured depth is 2 m 
deeper than the real depth. 

Raw data were corrected for the speed of sound using Carter Tables (RVS Level C 
stream prodep) and transferred into the pstar format (executable: depO). Data 
quality was consistently poor while steaming, but improved on station. Editing 
consisted of the removal of major spikes (plxyed), merging with daily GPS 
navigation (dep I) and averaging to 10 minute intervals (dep2) to smooth the 
multitude of small spikes which remained after the manual de-spiking stages. It 
should be noted that the quality of the resulting data files is somewhat 
dubious. Table 18.1 shows a comparison of the actual depth (as measured by the 
CTD pressure and altimeter with echo-sounder depth). 

The echosounder data suffered over steep topography and large spikes were seen 
in the raw data. At times, it was difficult to separate noise from data, in 
which cases linear interpolation was used to fill gaps produced by removal of 
such data. The echosounder underestimated depth in regions of steep topography, 
but, apart from that and a few occasions on which there was inexplicable strange 
behaviour, the edited bathymetry compared quite well to CTD pressure-derived 
plus altimeter depth on station.

The mean difference (CTD minus echosounder) for all points is -55.15 m (s.d. 
341.97).  Excluding all points with absolute difference greater than 38 m, the 
mean difference is -2.95 m (s.d. 8.87, N=120). 

Chris Wilson and Penny Holliday

Table 18.1 Comparison of actual depth with echo-sounder depth on station. Max 
press is maximum pressure (dbar) measured by the CTD, Max depth is max press 
converted to depth (metres), Alt is altimeter height off bottom at closest 
approach (metres), Est depth is max depth plus Alt (metres), PES depth is depth 
measured by echosounder, corrected for sound speed variation via Carter's Tables 
(metres), and Diff is Est depth minus PES depth (metres). 

	Max	Max	Alt	Est	PES	Diff	    Notes
Station	Press	Depth	Depth	Depth	Est-	 m
					PES
	 m	 m	 m	 m	 m	
--------------------------------------------------------------------------
13415	3663.0	3609.4	 95.5	3704.9	3706.6	   -1.7
13416	3961.0	3900.3	205.4	4105.7	3954.0	  151.8
13417	4217.0	4149.9	  8.6	4158.5	4164.0	   -5.5
13418	1075.0	1065.3	 58.8	1124.1	4281.3	-3157.2	   Cast abandoned
13419	4333.0	4262.8	 10.5	4273.3	4280.1	   -6.8
13420	4425.0	4352.3	-29.0	4323.3	4365.3	  -42.0
13421	4401.0	4328.8	-23.8	4305.0	4337.6	  -32.6
13422	4385.0	4313.0	  9.6	4322.6	4329.0	   -6.3
13423	4427.0	4353.8	 10.0	4363.8	4368.0	   -4.3
13424	4501.0	4425.7	  8.4	4434.0	4429.3	    4.7
13425	4539.0	4462.5	 10.2	4472.7	4475.0	   -2.3
13426	4597.0	4518.8	  9.2	4528.0	4518.1	    9.8
13427	4639.0	4559.5	  7.5	4566.9	4571.6	   -4.7
13428	4725.0	4642.9	  8.7	4651.6	4656.8	   -5.2
13429	4773.0	4689.4	  9.1	4698.5	4703.9	   -5.3
13430	4809.0	4724.2	  8.0	4732.2	4740.7	   -8.5
13431	4829.0	4743.5	  9.2	4752.7	4762.4	   -9.7
13432	4835.0	4749.1	  9.4	4758.5	4767.5	   -9.0
13433	4905.0	4816.9	  5.7	4822.7	4828.1	   -5.5
13434	4897.0	4809.0	  6.8	4815.8	4820.6	   -4.8
13435	4933.0	4843.7	  9.6	4853.4	4848.5	    4.9
13436	5003.0	4911.5	  3.6	4915.1	4909.7	    5.4
13437	5009.0	4917.1	 10.2	4927.3	4933.5	   -6.2
13438	5031.0	4938.3	  9.9	4948.2	4953.7	   -5.6
13439	5041.0	4947.8	 12.1	4959.8	4964.7	   -4.9
13440	5077.0	4982.5	  5.2	4987.7	4991.3	   -3.6
13441	5199.0	5100.6	  9.1	5109.7	5121.5	  -11.8
13442	5355.0	5251.6	 11.0	5262.6	5280.1	  -17.5
13443	5405.0	5299.8	  9.5	5309.3	5325.3	  -16.0
13444	5361.0	5256.9	  9.8	5266.7	5282.8	  -16.1
13445	5339.0	5235.4	  5.2	5240.6	5248.2	   -7.6
13446	5215.0	5115.0	  9.3	5124.3	5221.7	  -97.3
13447	5329.0	5225.3	  8.2	5233.4	5218.9	   14.5
13448	5383.0	5277.3	  8.3	5285.6	5216.2	   69.4
13449	5243.0	5141.5	  9.6	5151.1	5213.5	  -62.4
13450	3935.0	3870.0	 14.0	3884.0	5186.4	-1302.4	   PES problems
13451	4899.0	4807.4	  9.8	4817.2	4815.0	    2.2
13452	5185.0	5084.6	  7.3	5091.9	5093.3	   -1.4
13453	4483.0	4402.9	  9.3	4412.2	5067.3	 -655.1	   PES problems
13454	4825.0	4735.0	  6.1	4741.0	4746.3	   -5.3
13455	4737.0	4649.3	 11.5	4660.8	4661.8	   -1.0
13456	4839.0	4748.1	  9.1	4757.2	4777.4	  -20.2
13457	4993.0	4897.3	 10.0	4907.2	4919.8	  -12.5
13458	4781.0	4691.4	  9.0	4700.3	4705.7	   -5.4
13459	2793.0	2752.8	  9.3	2762.1	3011.7	 -249.6
13460	2355.0	2323.3	  9.3	2332.6	2219.0	  113.6
13461	4243.0	4167.9	 10.7	4178.7	4185.2	   -6.5
13462	5611.0	5494.5	  7.2	5501.7	5041.6	  460.1	   Steep topog
13463	4059.0	3988.5	  6.0	3994.5	3969.5	   24.9
13464	4063.0	3992.2	  9.4	4001.5	3896.5	  105.0
13465	4311.0	4233.3	  9.1	4242.3	4249.4	   -7.0
13466	4391.0	4310.9	  7.6	4318.5	4324.3	   -5.8
13467	4605.0	4518.6	  9.5	4528.0	4529.9	   -1.9
13468	4921.0	4825.0	  8.6	4833.6	4838.9	   -5.3
13469	4941.0	4844.1	  9.8	4854.0	4863.3	   -9.3
13470	4597.0	4510.2	 10.8	4521.0	4516.6	    4.4
13471	4625.0	4537.1	  7.5	4544.7	4556.8	  -12.1
13472	4433.0	4350.5	  1.6	4352.1	4408.8	  -56.7
13473	4103.0	4029.4	  8.4	4037.9	4046.6	   -8.7
13474	4481.0	4396.7	 11.0	4407.7	4413.8	   -6.1
13475	3929.0	3859.7	  9.4	3869.1	3890.4	  -21.3
13476	4475.0	4390.5	  8.8	4399.3	4404.0	   -4.8
13477	3983.0	3911.9	  9.5	3921.4	3933.0	  -11.5
13478	3707.0	3642.9	  7.3	3650.3	3661.3	  -11.0
13479	3695.0	3631.1	  8.5	3639.6	3646.8	   -7.3
13480	3791.0	3724.4	  9.3	3733.8	3739.3	   -5.6
13481	4161.0	4084.5	  8.1	4092.7	4095.3	   -2.6
13482	4555.0	4467.3	  9.0	4476.4	4483.0	   -6.6
13483	4561.0	4473.1	  8.9	4482.0	4487.3	   -5.3
13484	4315.0	4234.2	  9.4	4243.6	4248.7	   -5.1
13485	3613.0	3551.0	  8.2	3559.2	3564.8	   -5.7
13486	2437.0	2401.5	  7.3	2408.8	2381.6	   27.2
13487	1489.0	1470.4	  5.3	1475.7	1455.3	   20.4
13488	 339.0	 335.6	  9.6	 345.2	 343.5	    1.7
13489	2809.0	2765.6	  8.9	2774.6	2778.8	   -4.2
13490	2723.0	2681.4	  9.3	2690.6	2678.0	   12.6
13491	2313.0	2279.6	  9.7	2289.4	2286.8	    2.6
13492	1415.0	1397.3	  8.2	1405.5	1408.9	   -3.4
13493	1393.0	1375.6	  9.0	1384.6	1387.6	   -3.0
13494	1623.0	1601.9	  9.1	1610.9	1610.8	    0.1
13495	1135.0	1121.4	 10.0	1131.4	1134.2	   -2.8
13496	1471.0	1452.2	 10.1	1462.3	1462.3	    0.0
13497	1381.0	1363.6	 10.2	1373.8	1375.4	   -1.6
13498	 975.0	 963.5	  6.9	 970.5	 970.6	   -0.2
13499	1167.0	1152.7	  8.6	1161.3	1164.5	   -3.2
13500	1665.0	1642.7	  8.9	1651.6	1653.4	   -1.8
13501	2605.0	2564.6	  8.7	2573.3	2573.0	    0.4
13502	2873.0	2826.7	  9.1	2835.8	2838.7	   -2.9
13503	2801.0	2756.2	  7.0	2763.2	2768.4	   -5.2
13504	2755.0	2711.1	  8.8	2719.9	2726.4	   -6.5
13505	 201.0	 198.9	  9.9	 208.8	2119.7	-1910.9	   PES problems
13506	1139.0	1124.6	  9.9	1134.5	1732.3	 -597.7	   PES problems
13507	1637.0	1614.6	  9.6	1624.2	1627.7	   -3.4
13508	1813.0	1787.6	  9.4	1796.9	1803.7	   -6.8
13509	2245.0	2211.5	  8.8	2220.3	2229.1	   -8.8
13510	2427.0	2389.9	  8.3	2398.1	2406.4	   -8.2
13511	2553.0	2513.3	  9.7	2523.1	2531.0	   -7.9
13512	2719.0	2675.9	 10.1	2686.0	2692.1	   -6.1
13513	2517.0	2478.3	  9.4	2487.7	2485.3	    2.3
13514	1857.0	1831.2	  9.3	1840.5	1836.0	    4.5
13515	 975.0	 963.4	  9.0	 972.4	 969.2	    3.2
13516	 833.0	 823.3	  7.7	 831.0	1037.5	 -206.5
13517	1175.0	1160.5	  9.6	1170.1	1135.1	   35.0
13518	1221.0	1205.8	  7.7	1213.6	1218.3	   -4.7
13519	 975.0	 963.4	  9.2	 972.6	 927.1	   45.5
13520	 563.0	 556.8	  7.9	 564.7	 548.1	   16.6
13521	 109.0	 107.9	  8.5	 116.4	 115.7	    0.7
13522	1097.0	1083.7	  8.1	1091.9	1091.5	    0.4
13523	1661.0	1638.9	  7.3	1646.1	1650.5	   -4.4
13524	1815.0	1790.2	 10.6	1800.8	1803.6	   -2.8
13525	2035.0	2006.2	  9.0	2015.2	2015.7	   -0.5
13526	 587.0	 580.6	  8.5	 589.1	 589.3	   -0.2
13527	2235.0	2202.4	  8.5	2210.9	2215.6	   -4.6
13528	1945.0	1917.9	  7.1	1925.0	 928.6	   -3.5
13529	1453.0	1434.4	  7.6	1441.9	1438.3	    3.7
13530	 303.0	 299.9	  8.9	 308.8	 307.3	    1.5
13531	 131.0	 129.7	  8.5	 138.2	 266.6	 -128.4
13532	 175.0	 173.3	  8.9	 182.2	 181.3	    1.0
13533	 517.0	 511.5	  9.8	 521.3	 523.3	   -2.0
13534	1323.0	1306.5	  8.9	1315.4	1316.5	   -1.1
13535	1869.0	1843.5	  5.0	1848.5	1852.5	   -4.0
13536	2229.0	2196.8	  9.4	2206.2	2212.9	   -6.7
13537	2459.0	2422.2	  7.2	2429.4	2437.2	   -7.8
13538	2741.0	2698.3	  9.4	2707.6	2499.1	  208.5
13539	2681.0	2639.5	  8.3	2647.9	2654.7	   -6.8
13540	2215.0	2183.0	 11.4	2194.4	2188.5	    5.8
13541	1743.0	1719.6	  9.4	1729.1	1732.4	   -3.3
13542	1155.0	1141.0	  8.0	1149.0	1147.6	    1.5
13543	 569.0	 562.9	  8.8	 571.6	 569.9	    1.8
13544	 851.0	 841.3	  9.0	 850.3	 842.9	    7.3
13545	1845.0	1820.0	  9.8	1829.8	1830.6	   -0.8
13546	2503.0	2465.5	  9.5	2474.9	2479.5	   -4.5
13547	2433.0	1397.0	  8.3	2405.3	2412.0	   -6.7
13548	2777.0	2733.8	  2.0	2735.8	2747.3	  -11.5
13549	3009.0	2960.8	 12.3	2973.1	2977.8	   -4.7
13550	2305.0	2271.7	 10.2	2281.8	2280.7	    1.2
13551	1355.0	1338.3	  9.4	1347.7	1345.0	    2.6
13552	 449.0	 444.4	  8.5	 452.9	 452.3	    0.5
13553	 319.0	 315.8	  8.8	 324.6	 350.4	  -25.8

19	SCIENTIFIC INSTRUMENTATION

19.1	Surfmet

The Surfmet system, which combines the old Met and TSG systems ran continuously 
for the duration of the cruise with data logged to level B and also sent to the 
OTD Met system via a serial link. 

The remote temperature sensor measuring incoming non-toxic water temperature was 
suspected of jumping and drifting. This was replaced with a spare but this too 
was found to jump at certain times. This may be attributable to the physical 
properties of the non-toxic system which may cause some heat generation/loss 
whilst on/off station. It was not always apparent though and requires further 
observation. 

Prior to cruise D232 a new non-toxic pipe system was installed. This is plastic 
coated piping and there is a direct feed to the TSG flow-through system. The old 
header tank is now replaced by a vortex debubbler which operates at 40-50 1 
min^-1. with small volume, thus reducing lag time. A flow-through 
transmissometer and fluorometer are fed from the same supply as the TSG. 

The output from the TSG was modified to provide an output to the CO2 measuring 
equipment, although flow to the TSG was reduced it appears to have had no 
detrimental effect. 

The windvane of the Met system is oriented so that zero degrees is to Port. For 
this cruise however, the crossarm which supports it and the anemometer was 
rotated so that zero degrees was forward. 

19.2	ADCP

The previous cruise showed that although one of the transducers four beams was 
defective, the ADCP could still operate using three beams. At first the data 
appeared to be good but halfway into the cruise, the defective third beam 
appeared to be producing some bad signals. This meant that data signals of bins 
deeper than 200 m were corrupted. The third beam signals were then grounded at 
the receiver board in the deck unit and the problem was resolved. Data down to 
400 m then appeared to be good and matched closely with the LADCP which was 
being used on the cruise. 

19.3	EchoSounder

During the early part of the cruise the echosounder suffered from considerable 
noise. This meant that there were a lot of drop outs and false depths given on 
the digital output, although it was still possible to see what the depth was 
from the scrolling display. About two weeks into the cruise this noise seemed to 
disappear but was replaced by weak signals, which also produces a lot of depth 
errors. This problem was less apparent in depths less than 2500 m where the 
soundings were consistently good. The problem appeared to be with the 
transmission from the deck unit but since the latter part of the cruise was 
shallow no further investigations were carried out. 

19.4	SBWR

The system was reinstalled prior to this cruise after calibration and fitting of 
valves to the inlets. A fault was found with the Port Pressure transducer but 
this was eventually traced to a broken wire in the signal circuit. The SBWR ran 
continuously throughout the cruise with a change of sampling parameters midway 
through in order to optimise the statistical analysis. 

19.5	XBT

The XBT system was used to deploy about 35 probes, including T5s and T7s in the 
latter part of the cruise. The launching and data collection worked fine but the 
GOES transmitter buffer was full and didn't empty at the scheduled transmission 
time. 

Dave Jolly

20	SCIENTIFIC ENGINEERING

Cruise 233 consisted of a 139 CTD deployments through the starboard gantry, 
using the 20 ton Cobra winch system and the 10 ton Cobra winch system. Also in 
use were the Non toxic systems and Milii pore water plant. A few minor problems 
occurred during the cruise but none led to any major loss of equipment or 
scientific down time. 

20.1	Starboard Gantry

The gantry worked well and caused no problems throughout the cruise. 

20.2	20 ton Cobra winch system

This system was used with the deep tow electrical conducting wire for the 
deepest casts. There were no problems with this system after the initial setting 
up of the back tension loads on the storage drum. Trials were undertaken by RVS 
technicians to try to determine an intermittent fault with one of the boost 
pumps, however this did not interfere with the scientific cruise programme. 

20.3	10 ton Cobra winch system

This system was used for the majority of the casts and in general worked well. 
There were, however, a few small problems. 

Winch spooling

The recovery of the wire had to be slowed on a few occasions to help to prevent 
wire distortion. This problem seemed to cure itself after a few deep casts and 
there were no more problems encountered.

Diverter sheave bearing 

One of the inboard sheaves bearings collapsed and needed repair. These repairs 
were undertaken by the RVS technicians. A new bearing was turned on the lathe, 
fitted, and the unit reassembled. The sheave gave no more problems. 

Retermination of the CTD wire

An electrical fault on the termination was found. The wire was cropped at 135 m 
and reterminated. After being load tested the wire was put into service and gave 
no more problems.

20.4	Non toxic

A few leaks followed the refit modifications but no serious problems occurred. 

20.5	Milii Q water plant

The system was serviced by RVS technicians and a circuit board replaced, no 
major problems were encountered. 

Chris Rymer, Tony Poole and Rhys Roberts

---------------------------------------------------------------------------
APPENDIX A

CHAOS CTD STATION INFORMATION

The following table gives information for all CTD stations. The data headings 
are as follows

Ship/crs expocode:	the cruise code is constructed from the country code 74 
			(UK) ship code DI (Discovery), number 233 (cruise number), and 
			extension (leg number).
Stn nbr:		station number
Cst nbr:		cast number
Cst type:		designation for cast type is ROS (for rosette plus CTD etc) 
			throughout
Date:			date format is mmddyy throughout
Day:			Julian Day
Start, Btrn, End time:	start, bottom, and end time for the cast - format is 
			hhmm. throughout
Lat, Long:		positions corresponding to the above in deg min
Unc Depth:		uncorrected depth (metres) from the echosounder (PES fish)
Alt:			Height off bottom (meters) at closest approach as measured by 
			the altimeter
Wire out:		metres of wire deployed at bottom of cast
Max press:		Maximum CTD pressure recorded on the cast
Nbr bods:		number of rosette bottles samples on each cast
Parameters:		samples collected for the following analysis

1	salinity	26	ph
2	Oxygen		27	CFC- 113
3	silicate	28	carbon tetrachloride
4	nitrate		34	chl a
5	nitrite		35	phaeophytin
6	phosphate	36	plant pigments HPLC analysis
7	CFC- 11		37	phytoplankton taxonomy
8	CFC- 12		38	DON
24	alkalinity	39	halocarbons other than CFCs

Comments

APPENDIX A (continued)

Ship/crs	Stn	Cst	Cst	Date	Day	Start	Btm	End	Lat		Long		Unc	Alt	Wire	Max	Nbr	Parameters				Comments
expocode	nbr	nbr				time	time	time					depth	m	out	pres	btls		
-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
74DI233/1	13414	1	ROS	240498	114	09:20	11:13	12:36	26 14.8 N	17 15.5 W	3577	9.9	3594	3621	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	Test cast
74DI233/1	13415	1	ROS	260498	116	00:42	02:09	04:15	20 00.4 N	20 45.4 W	3705	-999	3610	3663	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	Begin 20°W section
74DI233/1	13416	1	ROS	260498	116	07:36	09:09	03:21	20 30.8 N	20 52.9 W	4106	-999	3920	3961	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13417	1	ROS	260498	116	14:20	15:54	17:47	21 00.0 N	21 00.1 W	4158	8.6	4152	4217	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13418	1	ROS	260498	116	20:52	-	22:18	21 30.2 N	21 04.0 W	1124	-999	-	1075	-	-					Abandoned 800 m
74DI233/1	13419	1	ROS	270498	117	00:24	02:07	04:06	21 30.2 N	21 03.8 W	4273	10.5	4199	4333	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13420	1	ROS	270498	117	07:31	09:15	11:18	22 01.0 N	21 06.3 W	4323	9.0	4290	4425	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13421	1	ROS	270498	117	14:52	16:28	18:20	22 29.8 N	21 08.3 W	4305	9.0	4261	4401	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13422	1	ROS	270498	117	22:10	23:07	01:54	23 00.1 N	21 10.0 W	4323	9.6	4243	4385	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13423	1	ROS	280498	118	06:59	08:46	10:55	23 29.8 N	21 11.8 W	4364	10.0	4288	4427	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13424	1	ROS	280498	118	14:05	17:00	18:59	23 59.9 N	21 20.6 W	4434	8.4	4364	4501	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13425	1	ROS	280498	118	22:02	23:03	02:04	24 30.1 N	21 20.2 W	4473	10.2	4450	4539	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13426	1	ROS	290498	119	05:24	07:12	09:26	24 59.7 N	21 20.3 W	4528	9.2	4450	4597	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13427	1	ROS	290498	119	12:37	14:39	16:52	25 30.4 N	21 19.6 W	4567	7.5	4494	4639	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13428	1	ROS	290498	119	19:50	21:49	00:03	26 00.1 N	21 19.9 W	4652	8.7	4571	4725	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13429	1	ROS	300498	120	03:11	05:13	07:22	26 30.1 N	21 20.2 W	4699	9.1	4615	4773	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13430	1	ROS	300498	120	10:24	12:14	14:28	27 00.1 N	21 20.1 W	4732	8.0	4650	4809	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13431	1	ROS	300498	120	17:33	19:26	21:33	27 30.1 N	21 20.6 W	4753	9.2	4723	4829	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13432	1	ROS	010598	121	00:28	02:27	04:39	28 00.2 N	21 19.8 W	4758	9.4	4675	4835	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13433	1	ROS	010598	121	07:40	09:44	12:09	28 30.0 N	21 20.3 W	4823	5.7	4740	4905	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13434	1	ROS	010598	121	15:09	17:00	19:01	29 00.3 N	21 20.6 W	4816	6.8	4733	4897	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13435	1	ROS	010598	121	22:02	00:09	02:38	29 29.8 N	21 19.6 W	4853	9.6	4767	4933	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13436	1	ROS	020598	122	06:05	08:03	10:39	29 59.5 N	21 19.6 W	4915	3.6	4855	5003	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13437	1	ROS	020598	122	14:09	16:13	18:23	30 30.2 N	21 20.0 W	4927	10.2	4914	5009	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13438	1	ROS	020598	122	21:43	23:50	02:12	31 00.6 N	21 20.4 W	4948	9.9	4932	5031	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13439	1	ROS	030598	123	05:31	07:39	09:50	31 31.0 N	21 19.5 W	4960	12.1	4965	5041	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13440	1	ROS	030598	123	13:14	15:31	17:51	31 59.9 N	21 19.9 W	4988	5.2	4983	5077	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13441	1	ROS	030598	123	21:14	23:32	02:11	32 30.0 N	21 20.3 W	5110	9.1	5093	5199	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13442	1	ROS	040598	124	05:21	07:33	10:00	33 00.4 N	21 19.1 W	5263	11.0	5248	5355	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13443	1	ROS	040598	124	13:06	15:28	18:04	33 30.3 N	21 19.7 W	5309	9.5	5300	5405	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13444	1	ROS	040598	124	21:07	23:24	02:02	33 59.9 N	21 20.0 W	5267	9.8	5252	5361	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13445	1	ROS	050598	125	05:18	07:37	10:01	34 30.9 N	21 20.7 W	5241	5.2	5243	5339	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13446	1	ROS	050598	125	13:12	15:34	18:03	35 00.4 N	21 20.0 W	5124	9.3	5109	5215	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13447	1	ROS	050598	125	22:02	00:13	02:33	35 29.8 N	20 49.2 W	5233	8.2	5229	5329	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13448	1	ROS	060598	126	06:38	08:51	11:58	36 00.0 N	20 19.9 W	5286	8.3	5233	5383	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13449	1	ROS	060598	126	15:32	17:33	20:01	36 30.1 N	19 59.7 W	5151	9.6	5137	5243	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13450	1	ROS	060598	126	22:55	00:27	02:23	37 00.3 N	19 59.6 W	3884	14.0	3864	3935	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13451	1	ROS	070598	127	05:24	07:14	09:26	37 30.3 N	20 00.1 W	4817	9.8	4806	4899	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13452	1	ROS	070598	127	12:06	14:04	16:21	37 59.9 N	20 00.6 W	5092	7.3	5082	5185	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13453	1	ROS	070598	127	19:14	21:08	22:57	38 29.8 N	19 59.5 W	4412	9.3	4407	4483	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13454	1	ROS	080598	128	01:50	03:38	05:37	38 59.9 N	20 00.0 W	4741	6.1	4728	4825	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13455	1	ROS	080598	128	08:36	11:16	13:15	39 29.8 N	19 59.5 W	4661	11.5	4652	4737	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13456	1	ROS	080598	128	16:25	18:12	20:15	40 00.1 N	20 00.2 W	4757	9.1	4743	4839	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13457	1	ROS	090598	129	23:05	01:04	03:09	40 29.9 N	20 00.1 W	4907	10.0	4891	4993	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13458	1	ROS	090598	129	07:11	08:10	10:14	40 59.7 N	19 59.4 W	4700	9.0	4690	4781	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13459	1	ROS	090598	129	13:13	14:27	16:04	41 30.1 N	19 59.6 W	2762	9.3	2751	2793	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13460	1	ROS	090598	129	19:09	20:14	21:21	42 00.1 N	19 59.6 W	2333	9.3	2320	2355	19	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13461	1	ROS	100598	130	00:36	02:24	04:28	42 30.4 N	20 00.1 W	4179	10.7	4162	4243	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13462	1	ROS	100598	130	13:58	16:10	18:27	43 01.0 N	20 00.7 W	5502	7.2	5435	5611	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13463	1	ROS	110598	131	05:40	07:21	09:09	43 30.3 N	20 01.0 W	3994	6.0	3939	4059	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13464	1	ROS	110598	131	12:39	14:26	16:05	43 59.9 N	20 00.1 W	4002	9.4	3928	4063	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13465	1	ROS	110598	131	19:15	21:04	22:52	43 29.9 N	20 00.3 W	4242	9.1	4166	4311	24	1-6, 7, 8, 27-28, 34-38, 39		Latitude is likely 44 29.9, not 43 29.9
74DI233/1	13466	1	ROS	120598	132	01:42	03:42	05:27	45 00.0 N	19 59.8 W	4318	7.6	4245	4391	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13467	1	ROS	120598	132	08:34	10:26	12:20	45 30.1 N	20 00.7 W	4528	9.5	4515	4605	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13468	1	ROS	120598	132	15:07	16:58	19:00	46 00.2 N	20 00.5 W	4834	8.6	4821	4921	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13469	1	ROS	120598	132	21:51	23:42	01:45	46 30.5 N	19 59.2 W	4854	9.8	4850	4941	24	1-6, 34-38,	
74DI233/1	13470	1	ROS	130598	133	04:34	06:23	08:26	46 59.6 N	19 59.0 W	4521	10.8	4527	4597	24	1-6, 24, 26, 34-38,	
74DI233/1	13471	1	ROS	130598	133	11:13	13:15	15:07	47 29.9 N	19 59.8 W	4545	7.5	4531	4625	24	1-6, 34-38	
74DI233/1	13472	1	ROS	130598	133	17:57	19:37	21:27	47 59.8 N	19 59.1 W	4352	1.6	4357	4433	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13473	1	ROS	140598	134	00:15	02:04	03:50	48 30.1 N	19 59.8 W	4038	8.4	4021	4103	24	1-6, 34-38	
74DI233/1	13474	1	ROS	140598	134	06:56	08:44	10:38	49 00.1 N	20 00.4 W	4408	11.0	4392	4481	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13475	1	ROS	140598	134	13:28	15:14	16:57	49 30.0 N	20 00.7 W	3869	9.4	3873	3929	24	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13476	1	ROS	140598	134	19:55	21:40	23:38	49 58.9 N	20 00.8 W	4399	8.8	4387	4475	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13477	1	ROS	150598	135	02:27	04:15	06:07	50 29.8 N	19 59.9 W	3921	9.5	3906	3983	24	1-6, 34-38	
74DI233/1	13478	1	ROS	150598	135	09:01	10:30	12:17	50 59.8 N	20 00.2 W	3650	7.3	3635	3707	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13479	1	ROS	150598	135	15:24	16:52	18:34	51 29.7 N	20 00.6 W	3640	8.5	3625	3695	24	1-6, 34-38	
74DI233/1	13480	1	ROS	150598	135	21:32	23:10	00:51	51 59.8 N	20 00.4 W	3734	9.3	3718	3791	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	Leave 20°W section
74DI233/1	13481	1	ROS	160598	136	03:38	05:20	07:06	52 01.4 N	19 14.0 W	4093	8.1	4080	4161	24	1-6, 7, 8, 27-28, 34-38, 39		Begin Rockall 52°N section
74DI233/1	13482	1	ROS	160598	136	09:43	11:30	13:25	52 02.4 N	18 30.1 W	4476	9.0	4464	4555	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13483	1	ROS	160598	136	16:02	17:48	19:41	52 03.2 N	17 44.5 W	4482	8.9	4468	4561	24	1-6, 34-38	
74DI233/1	13484	1	ROS	160598	136	22:40	00:21	02:13	52 03.7 N	16 59.9 W	4244	9.4	4231	4315	24	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13485	1	ROS	170598	137	04:51	06:21	08:00	52 04.9 N	16 15.5 W	3559	8.2	3546	3613	23	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13486	1	ROS	170598	137	10:42	11:44	13:02	52 07.3 N	15 29.8 W	2409	7.3	2411	2437	19	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13487	1	ROS	170598	137	14:56	15:36	16:23	52 07.9 N	15 00.5 W	1476	5.3	1476	1489	14	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13488	1	ROS	170598	137	19:24	19:38	19:54	52 10.1 N	14 10.0 W	345	9.6	329	339	8	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	End of Rockall 52°N section
74DI233/1	13489	1	ROS	180598	138	15:46	16:57	18:30	52 30.2 N	19 59.6 W	2775	8.9	2761	2809	20	1-6, 7, 8, 27-28, 34-38, 39		Return to 20°W section
74DI233/1	13490	1	ROS	180598	138	20:55	22:02	23:16	53 02.2 N	19 59.6 W	2691	9.3	2676	2723	20	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13491	1	ROS	190598	139	02:04	03:05	04:13	53 30.0 N	20 00.1 W	2289	9.7	2275	2313	18	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13492	1	ROS	190598	139	06:49	07:29	08:14	54 00.4 N	19 59.6 W	1406	8.2	1391	1415	15	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13493	1	ROS	190598	139	10:47	11:28	12:11	54 30.0 N	19 59.9 W	1385	9.0	1370	1393	14	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13494	1	ROS	190598	139	14:57	15:40	16:32	54 59.9 N	20 00.2 W	1611	9.1	1595	1623	15	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13495	1	ROS	190598	139	19:14	19:48	20:25	55 29.9 N	19 59.8 W	1131	10.0	1117	1135	13	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13496	1	ROS	200598	140	23:14	00:03	00:47	56 00.4 N	19 59.9 W	1462	10.1	1149	1471	13	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13497	1	ROS	200598	140	03:33	04:10	04:57	56 29.9 N	20 00.1 W	1374	10.2	1359	1381	14	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13498	1	ROS	200598	140	07:38	08:06	08:40	56 59.9 N	19 59.7 W	970	6.9	960	975	12	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13499	1	ROS	200598	140	11:19	11:55	12:34	57 29.9 N	19 59.4 W	1161	8.6	1146	1167	12	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13500	1	ROS	200598	140	15:14	16:26	17:15	58 00.4 N	19 58.9 W	1652	8.9	1638	1665	16	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13501	1	ROS	200598	140	19:47	20:50	21:55	58 30.1 N	20 00.3 W	2573	8.7	2559	2605	19	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13502	1	ROS	210598	141	00:38	01:58	03:14	59 00.1 N	19 59.8 W	2836	9.1	2826	2873	20	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13503	1	ROS	210598	141	06:02	07:10	08:30	59 29.4 N	19 59.4 W	2763	7.0	2759	2801	21	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13504	1	ROS	210598	141	11:26	12:36	13:57	59 59.7 N	20 00.2 W	2720	8.8	2705	2755	20	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13505	1	ROS	220598	142	06:44	06:57	07:10	63 19.3 N	19 59.5 W	209	9.9	194	201	7	1-6, 7, 8, 27-28, 34-38, 39		Most northerly  station
74DI233/1	13506	1	ROS	220598	143	21:21	21:45	22:22	63 00.0 N	19 59.9 W	1135		1120	1139	13	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13507	1	ROS	230598	143	01:25	02:07	02:54	62 30.2 N	20 00.1 W	1624	9.6	1610	1637	14	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13508	1	ROS	230598	143	05:58	06:47	07:42	62 00.2 N	19 59.5 W	1797	9.4	1782	1813	16	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13509	1	ROS	230598	143	10:34	11:32	12:35	61 29.7 N	20 00.1 W	2220	8.8	2209	2245	19	1-6, 7, 8, 27-28, 34-38, 39	
74DI233/1	13510	1	ROS	230598	143	15:20	16:16	17:22	60 59.9 N	20 00.2 W	2398	8.3	2387	2427	19	1-6, 7, 8, 24, 26, 27-28, 34-38, 39	
74DI233/1	13511	1	ROS	240598	144	19:57	21:02	22:13	60 29.7 N	19 59.2 W	2523	9.7	2507	2553	19	1-6, 7, 8, 27-28, 34-38, 39		End 20°W section
74DI233/1	13512	1	ROS	240598	144	02:38	03:50	05:03	59 43.1 N	19 13.8 W	2686	10.1	2670	2719	20	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13513	1	ROS	240598	144	07:50	08:53	10:02	59 26.0 N	18 02.4 W	2488	9.4	2474	2517	21	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13514	1	ROS	240598	144	10:48	11:37	12:45	59 20.8 N	18 23.4 W	1840	9.3	1828	1857	17	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13515	1	ROS	240598	144	14:43	15:10	15:45	59 07.8 N	17 38.4 W	972	9.0	963	975	12	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13516	1	ROS	240598	144	17:29	18:00	18:32	58 58.1 N	17 11.6 W	831	7.7	817	833	11	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13517	1	ROS	250598	145	20:50	21:24	22:00	58 42.4 N	16 38.2 W	1170	9.6	1154	1175	12	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13518	1	ROS	250598	145	23:59	00:40	01:17	58 30.1 N	16 05.1 W	1214	7.7	1199	1221	12	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13519	1	ROS	250598	145	03:21	03:51	04:29	58 18.1 N	15 29.7 W	973	9.2	977	975	12	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13520	1	ROS	250598	145	06:59	07:18	07:45	58 02.0 N	14 45.1 W	565	7.9	550	563	10	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13521	1	ROS	250598	145	11:43	11:50	12:02	57 34.8 N	13 38.0 W	116	8.5	103	109	6	1-6					Begin Rockall 57°N section (Ellett line)
74DI233/1	13522	1	ROS	250598	145	14:26	14:56	15:33	57 32.3 N	12 51.9 W	1092	8.1	1079	1097	12	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13523	1	ROS	250598	145	16:32	17:16	18:03	57 31.9 N	12 37.8 W	1646	7.3	1635	1661	16	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13524	1	ROS	260598	146	19:21	20:15	21:11	57 31.3 N	12 14.7 W	1801	10.6	1791	1815	16	1-6, 7, 8, 27-28, 39	
74DI233/1	13525	1	ROS	260598	146	23:32	00:32	01:35	57 28.5 N	11 32.4 W	2015	9.0	2002	2035	16	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13526	1	ROS	260598	146	03:19	03:43	04:08	57 27.2 N	11 05.2 W	589	8.5	573	587	10	1-6	
74DI233/1	13527	1	ROS	260598	146	06:49	07:45	08:50	57 18.0 N	10 23.1 W	2211	8.5	2197	2235	18	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13528	1	ROS	260598	146	11:21	12:11	13:10	57 09.0 N	09 41.8 W	1925	7.1	1913	1945	17	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13529	1	ROS	260598	146	14:25	15:07	15:58	57 06.3 N	09 25.4 W	1442	7.6	1433	1453	15	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13530	1	ROS	260598	146	17:02	17:20	17:37	57 03.1 N	09 13.0 W	309	8.9	294	303	8	1-6, 7, 8, 27-28, 39	
74DI233/1	13531	1	ROS	270598	147	18:36	18:44	18:57	56 59.9 N	08 59.8 W	138	8.5	123	131	6	1-6, 34-37				End Rockall 57°N section (Ellett line)
74DI233/1	13532	1	ROS	270598	147	00:58	01:09	01:23	55 51.6 N	09 10.1 W	182	8.9	165	175	7	1-6					Begin Rockall 56°N section
74DI233/1	13533	1	ROS	270598	147	02:06	02:27	02:47	55 52.8 N	09 19.8 W	521	9.8	506	517	9	1-6	
74DI233/1	13534	1	ROS	270598	147	03:48	04:29	05:15	55 53.3 N	09 34.7 W	1315	8.9	1302	1323	14	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13535	1	ROS	270598	147	06:21	07:16	08:13	55 54.8 N	09 49.2 W	1849	5.0	1850	1869	16	1-6, 7, 8, 27-28, 39	
74DI233/1	13536	1	ROS	270598	147	09:33	10:32	11:38	55 55.7 N	10 11.3 W	2206	9.4	1032	2229	18	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13537	1	ROS	270598	147	13:46	14:46	15:55	56 00.5 N	10 49.9 W	2429	7.2	2419	2459	19	1-6, 7, 8, 27-28, 39	
74DI233/1	13538	1	ROS	270598	147	18:58	20:13	21:28	56 03.6 N	11 44.9 W	2708	9.4	2694	2741	20	1-6, 7, 8, 27-28, 39	
74DI233/1	13539	1	ROS	280598	148	00:38	01:49	03:03	56 07.9 N	12 44.9 W	2648	8.3	2636	2681	20	1-6, 7, 8, 27-28, 39	
74DI233/1	13540	1	ROS	280598	148	06:25	07:21	08:25	56 12.9 N	13 47.7 W	2194	11.4	2200	2215	18	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13541	1	ROS	280598	148	09:16	10:03	11:00	56 13.6 N	14 03.9 W	1729	9.4	1716	1743	16	1-6, 7, 8, 27-28, 39	
74DI233/1	13542	1	ROS	280598	148	11:43	12:20	13:02	56 14.9 N	14 14.2 W	1149	8.0	1134	1155	13	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13543	1	ROS	280598	148	14:01	14:21	14:49	56 15.9 N	14 26.2 W	572	8.8	558	569	12	1-6					End Rockall  56°N section
74DI233/1	13544	1	ROS	280598	148	20:59	21:24	21:52	55 30.9 N	14 50.3 W	850	9.0	840	851	10	1-6, 7, 8, 27-28, 39			Beginning Rockall 54°N section
74DI233/1	13545	1	ROS	290598	149	23:33	00:22	01:14	55 18.1 N	15 31.7 W	1830	9.8	1819	1845	16	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13546	1	ROS	290598	149	02:25	03:26	04:49	55 12.8 N	15 23.1 W	2475	9.5	2460	2503	23	1-6, 7, 8, 27-28, 34-37, 39	
74DI233/1	13547	1	ROS	290598	149	07:10	08:17	09:39	54 55.9 N	14 54.7 W	2405	8.3	2392	2433	21	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13548	1	ROS	290598	149	12:19	13:25	14:38	54 34.9 N	14 20.2 W	2736	2.0	2730	2777	22	1-6, 7, 8, 27-28, 39	
74DI233/1	13549	1	ROS	290598	149	17:55	19:07	20:38	54 14.7 N	13 45.2 W	2973	12.3	2977	3009	24	1-6, 7, 8, 24, 26, 27-28, 39	
74DI233/1	13550	1	ROS	290598	149	22:00	23:09	00:24	54 06.4 N	13 32.3 W	2282	10.2	2203	2305	22	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13551	1	ROS	300598	150	01:44	02:26	03:14	54 02.3 N	13 25.6 W	1348	9.4	1334	1355	17	1-6, 7, 8, 24, 26, 27-28, 34-37, 39	
74DI233/1	13552	1	ROS	300598	150	0.18	04:37	04:55	53 55.0 N	13 18.1 W	453	8.5	440	449	9	1-6	
74DI233/1	13553	1	ROS	300598	150	06:42	06:55	07:09	53 48.1 N	13 10.1 W	325	8.8	312	319	8	1-6, 7, 8, 27-28, 39			End Rockall 54°N section

-----------------------------------------------------------------------------------------------------
APPENDIX B

CHAOS XBT STATION INFORMATION

The following table gives information for all XBT stations.  The data headings 
are as follows

Stn nbr:    station number
Date:	    date format is mmddyy throughout
Day:	    Julian Day
Time:	    format is hhmm throughout
Lat, Long:  positions corresponding to the above in deg min
Speed:	    in knots
Heading:    degrees North
Depth:	    uncorrected depth from the echosounder (PES fish) in metres


Stn	Date	Day	Time	Probe	Probe	Lat		Long		Speed	Hdg	Depth	  Comment
nbr				type	No								Data		GOES
-----------------------------------------------------------------------------------------------------------------------------
1	250598	145	12:50	T7	019628	57 34.1 N	13 22.4 W	11.3	 87	 178	good		good
2	250598	145	13:35	T7	019627	57 33.3 N	13 07.2 W	11.1	 92	 225	good		good
3	260598	146	06:25	T7	019629	57 22.7 N	10 45.0 W	 -	105	 990	good		good
4	260598	146	11:15	T7	019630	57 12.9 N	10 00.0 W	 8.0	 99	2090	good		good
5	260598	146	13:40	T5	260767	57 07.8 N	09 35.0 W	 6.6	 91	1845	good		 bad
6	260598	146	16:20	T7	019631	57 05.4 N	09 21.1 W	 7.8	115	 970	good		 bad
7	260598	146	18:07	T7	019632	57 01.0 N	09 05.0 W	 8.7	 94	 150	good		 bad
8	260598	146	21:45	T7	019624	56 27.0 N	09 05.0 W	11.7	182	 428	good		 bad
9	260598	146	23:30	T7	019625	56 07.0 N	09 08.4 W	11.3	163	 195	 bad		 bad
10	270598	147	01:45	T7	019621	55 52.0 N	09 15.0 W	11.0	298	 335	good		 bad
11	270598	147	03:15	T7	019622	55 52.7 N	09 27.7 W	11.1	263	 982	good		 bad
12	270598	147	05:45	T5	260771	55 53.9 N	09 42.6 W	11.0	263	1690	good		 bad
13	270598	147	08:55	T5	260766	55 55.5 N	09 59.9 W	11.0	277	2100	good to 1350m	 bad
14	270598	147	12:36	T5	260763	55 58.0 N	10 30.3 W	 6.1	273	2267	good		 bad
15	270598	147	17:25	T5	260770	56 01.6 N	11 17.8 W	 5.9	271	2615	good		 bad
16	270598	147	23:03	T5	260769	56 05.9 N	12 15.0 W	 6.0	314	2721	good		 bad
17	280598	148	04:40	T5	260765	56 10.1 N	13 16.0 W	 6.0	263	2525	good		 bad
18		148	16:27	T7	019626	56 04.1 N	14 49.5 W	11.0	225	 363	good		 bad
19	280598	148	17:48	T7	019623	55 53.6 N	15 09.9 W	11.0	226	 365	good		 bad
20	280598	148	19:16	T7	041908	55 41.9 N	15 30.1 W	10.7	234	 522	good		 bad
21	280598	148	22:43	T7	041905	55 24.6 N	15 41.3 W	10.7	135	1355	good		 bad
22	290598	149	02:43	T5	260761	55 15.5 N	15 27.4 W	10.6	147	1968	good		 bad
23	290598	149	05:57	T5	260762	55 04.5 N	15 09.0 W	15.2	150	2250	good		 bad
24	300598	150	00:56	T5	260760	54 04.0 N	13 29.5 W	 6.8	157	1551	good		 bad
25	300598	150	03:45	T7	019705	53 58.5 N	13 22.0 W	 8.0	141	 920	good		 bad
26	300598	150	05:18	T7	041909	53 51.5 N	13 14.1 W	10.0	150	 360	good		 bad
27	300598	150	09:30	T7	041907	53 48.0 N	12 29.5 W	10.0	085	 350	good		 bad
28	300598	150	11:32	T7	041910	53 48.8 N	11 52.3 W	11.0	095	 340	good		 bad
29	300598	150	12:33	T7	041912	53 48.0 N	11 33.3 W	11.5	092	 250	good		 bad
30	300598	150	13:26	T7	041913	53 48.0 N	11 13.7 W	11.6	086	 190	good		 bad
31	300598	150	14:58	T7	041911	53 48.0 N	10 45.0 W	11.5	092	 154	good		 bad
32	300598	150	19:57	T7	041914	54 10.0 N	10 42.0 W	11.6	320	 180	good		 bad
33	300598	150	20:47	T7	041915	54 17.9 N	10 53.0 W	11.2	323	 302	good		 bad
34	300598	150	21:43	T7	041916	54 25.7 N	11 05.0 W	11.0	320	 428	good		 bad
35	300598	150	22:58	T5	260764	54 37.4 N	11 21.3 W	11.1	320	~ 2000	good to 1200 m	 bad

--------------------------------------------------------------------------------
APPENDIX C

LADCP COMMAND FILE

cmd		value		meaning
CR		1		Retrieve Parameters ( 0 = USER, 1 = FACTORY
PS		0		Show Sys Parms (0 = Xdcr, 1 = FLdr, 2 = VLdr, 3 = Mat, 4 = Seq)
CY				Clear BIT Log
CT		00		Restart Timeout ( 0 = OFF, 1 = TURNKEY, 2-59 = MINUTES)
EZ		0011101		Sensor Source (C;D;H;P;R;S;T)
EC		1500		Speed Of Sound (m s-1)
EX		11101		Coord Transform (Xform:Type; Tilts; 3Bm; Map)
WD		11 100 000	Data Out ( Vel; Cor; Int  PG; St; P0 P1; P2; P3)
WL		000,004		Water Reference Layer: Begin Cell ( 0 = OFF ), End Cell
WP		00001		Pings per Ensemble (0-16384)
WN		010		Number of depth cells (1-128)
WS		1600		Depth Cell Size (cm)
WF		1600		Blank After Transmit (cm)
WM		1		Profiling Mode (1-5)
WB		1		Bandwidth Control (0 = Wid, 1 = Nar)
WV		400		Mode 1 Ambiguity Velocity (cm s^-1 radial)
WE		0150		Error Velocity Threshold (0-5000 mm s^-1)
WC		056		Low Correlation Threshold (0  255 counts)
CP		255		Xmt Power ( 0=min, 255=max)
CL		0		Power Saver (0 = OFF, 1 = ON)
BP		001		BT Pings per Ensemble
BD		050		BT Delay Re-Acquire (# Ensembles)
BX		2500		BT Maximum Depth (80-9999 dm)
BL	000,0200,060		BT Layer: Min Size (dm), Near (dm), Far (dm)
BM		4		BT Mode (0-5)
TP		000100		Time between Ping Groups (min:sec.sec/100)
TE		00000200	Time per Ensemble (hrs:min:sec.sec/100)
&R		20		BT Transmit Percent Maximum
CF		11101		Flow Ctrl (EnsCyc;PngCyc;Binry;Ser;Rec)

* All figures are shown in PDF file.
