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CRUISE REPORT: AR25
(Updated OCT 2014)



Highlights
                            Cruise Summary Information

               Section Designation  AR25
Expedition designation (ExpoCodes)  74CD50_1
                  Chief Scientists  W. John Gould / NOC
                             Dates  1990 JUN 29 - 1990 JUL 22
                              Ship  RRS Charles Darwin
                     Ports of call  London - Aberdeen

                                                  64° 31.60" N
             Geographic Boundaries  17° 22.10" W                06° 03.80" W
                                                  60° 10.50" N

                          Stations  57 CTD stations
      Floats and drifters deployed  0
    Moorings deployed or recovered  7 current meter, 1 ADCP deployed

                              Contact Information:

                                  W. John Gould
      Visting Fellow (Former Director, WOCE International Project Office)
            National Oceanography Centre, University of Southampton
     Waterfront Campus • European Way • Southampton • Hampshire • SO14 3ZH
                                 United Kingdom
   Tel: +44 2380 596 207 • Fax: +44 2380 596 204 • Email: wjg@noc.soton.ac.uk























RRS Charles Darwin Cruise 50
29 Jun - 22 Jul 1990

Oceanography of the Iceland Basin
The fate of Iceland Scotland overflow water

Cruise Report No 221   1991



                                           Natural Environment Research Council












                       INSTITUTE OF OCEANOGRAPHIC SCIENCES

                                DEACON LABORATORY









                   Wormley, Godalming, Surrey, GU8 5UB, U.K.




                            Telephone:  0428 79 4141
                             Telex: 858833 OCEANS G
                              Telefax: 0428 79 3066












                         Director: Dr. C.P. Summerhayes






                      Natural Environment Research Council
                       INSTITUTE OF OCEANOGRAPHIC SCIENCES

                                DEACON LABORATORY

                              CRUISE REPORT NO. 221











                          RRS CHARLES DARWIN CRUISE 50
                               29 JUN-22 JUL 1990









                       Oceanography of the Iceland Basin:
                  the fate of Iceland Scotland overflow water







                              Principal Scientist
                                   W J Gould





                                      1991
  

  





                              DOCUMENT DATA SHEET

AUTHOR                                                              PUBLICATION
    GOULD, W J et al                                                DATE   1991
	

TITLE

    RRS Charles Darwin Cruise 50, 29 Jun-22 Jul 1990. Oceanography of the 
    Iceland Basin: the fate of Iceland Scotland overflow water.

REFERENCE

    Institute of Oceanographic Sciences Deacon Laboratory. Cruise Report, No. 
    221. 41 pp.


ABSTRACT

    The report provides a narrative and science project reports of a cruise to 
    the Iceland Basin of the NE Atlantic in summer of 1990. Work carried out 
    included the working of CTD and XBT sections, underway ADCP and Echo 
    Sounding, the deployment of moored current meters and the determination of 
    nutrient and dissolved oxygen characteristics.

KEYWORDS

    ADCP
    CHARLES DARWIN/RRS - cruise (1990) (50)
    CTD OBSERVATIONS
    CURRENT METERS
    ICELAND BASIN
    NUTRIENTS
    XBT

ISSUING ORGANISATION

        Institute of Oceanographic Sciences
        Deacon Laboratory
        Wormley, Godalming
        Surrey GU8 5UB. UK.                    Telephone Worrmley (0428) 684141
                                               Telex 868833 OCEANS G.
        Director: Colin Summerhayes DSc        Facsimile (0428) 683066

                                                                         £10.00
    Copies of this report are available from. The Library,        PRICE
  




CONTENTS			

  PERSONNEL
  CRUISE OBJECTIVES
  NARRATIVE
  REPORTS OF SCIENTIFIC WORK
    CTD Operations
    Water Sampling and Salinities
    Nutrient Determinations
    Oxygen Determinations
    Aluminum Determinations
    Digital Reversing Thermometers
    XBT Measurements
    Ship Mounted ADCP
    Mooring Operations
    Acoustics and P18
    Level A/B/C Processing
    PSTAR Processing
  ACKNOWLEDGEMENTS
  TABLES  
  FIGURES  
  


SCIENTIFIC PERSONNEL

  GOULD, W. John  IOSDL  Principal Scientist
  BACON, Sheldon  IOSDL
  BRANDON, Mark  IOSDL
  CHIPPINDALE, Marc  Univ. East Anglia
  DAVIES, Mike  RVS
  GOY, Keith M  IOSDL
  HYDES, David J.  IOSDL
  LLOYD, Rob. B  RVS
  MOSS, Karen  IOSDL (Industrial Year Student)
  PHILLIPS, Greg, R.J.  IOSDL
  RYMER, Chris  RVS
  SMITHERS, Mrs. Jill  IOSDL
  SMITHERS, John  IOSDL
  WOOLLEY, Marie   IOSDL (Industrial Year Student)
  WYNAR, John  RVS (To Wallsend only)
  


SHIP'S PERSONNEL

  AVERY, K.D.  Master
  LOUCH, A.R.  Chief Officer
  JACKSON, J.P.  2nd Officer
  ATKINSON, R.M.  3rd Officer
  ROWLANDS, D.C.  Chief Engineer
  ROBERTSON, GA.  2nd Engineer
  DEAN, S.F.    3rd Engineer
  EDGELL, P.E.  Electrician
  BAKER, J.G.L.  Radio Officer
  TREVASKIS, M.  CPO (Deck)
  





CRUISE OBJECTIVES

The cruise is one of a series (Challenger 15/87 (1987), Discovery 174 (1988), 
Charles Darwin 42 (1989), on which the magnitude and fate of the Overflow water 
from the Norwegian Sea crossing the series of ridges and channels between 
Scotland and Greenland have been studied.

On Charles Darwin 50 (1990) the objectives were

1)  To observe the path of the overflow water in the Iceland Basin on the south 
    side of the Iceland Faroes Ridge, using a lowered CTD, XBTs and ship 
    mounted ADCP (Acoustic Doppler Current Profiler).
2)  To determine the chemical properties (nutrients, dissolved oxygen and 
    aluminum concentration) of the Overflow and Atlantic water masses.
3)  To deploy an array of moored current and temperature recorders south of 
    Iceland.
4)  To deploy a moored ADCP on the Iceland-Faroes Ridge in support of Charles 
    Darwin Cr 51.





NARRATIVE

The scientific party joined the vessel in the Pool of London alongside HMS 
Belfast at 1430A 28-VI-90 (179). There was little in the way of equipment 
preparation that could be done since most gear was to be loaded the following 
day in Gt Yarmouth.

A photographer from the Guardian came to take pictures to accompany an article 
about the cruise (Guardian, 29-VI-90).

The vessel sailed at 1900A and made an uneventful passage overnight to Great 
Yarmouth where she berthed at 0930A (29th, 180)

Equipment from IOSDL was loaded, as were a number of items including the moored 
ADCP and its mooring hardware from RVS. Two staff from Hydrographic Dept 
Taunton were on hand to complete installation of the new automated XBT recorder 
supplied by the Hydrographic Dept.

Equipment was installed in the labs and a base plate for the CTD unit modified 
and bolted to the deck. Morag Stirling assembled and installed the fluorometer 
for Cruise 51 and Steve Alderson helped to install the P STAR data processing 
system. GPS position data were recorded throughout the port call in Gt Yarmouth 
in order to try to assess the effects of the deliberate downgrading of 
positional accuracy which had recently been imposed by the US Department of 
Defense.

It was clear by mid afternoon that we would not be able to catch the afternoon 
tide and sailing was therefore scheduled for 2300A.

A reporter from the Eastern Daily press who had seen the Guardian article 
visited the vessel in the afternoon.

The vessel sailed at 2330A after a delay due to pilots being busy. No 
scientific watches were kept overnight but navigation data were logged.

June 30th (181) opened overcast with a falling barometer and with the vessel 
making 12 kts northwards in a light sea. The scientific party continued 
preparing equipment. Thermosalinograph logging was started and calibration 
water samples from the non toxic seawater supply were taken at 4 hr intervals. 
ADCP logging was started at mid morning.

The vessel passed through Pentland Firth between 1030-100A (July 1, 182) in 
clear conditions but the weather worsened as we progressed northwestwards.

The vessel stopped at 1430A to deploy the PES fish and to test handling of the 
new CTD and multisampler package. The unit was deployed without bottles and 
with two 40 kg lead weights strapped to the bottom ring. The frame handled well 
and showed that it could be deployed and recovered with the ship's guard rails 
in place. The cantilever arm on the midships A frame seemed to steady the 
package quite well.

Course was resumed towards 60 15N 06 00W but with speed reduced to 7-8 kts due 
to weather.

At ca l600A the ship stopped so that severe noise and vibration in area of 
steering gear which had become apparent as the sea state had increased could be 
investigated. After considerable deliberation it was decided that there was a 
serious problem, (probably with the rudder), and we set course at reduced revs 
for Aberdeen.

The vessel arrived in Aberdeen by mid morning July 2nd (183). Divers were on 
hand to inspect the rudder and propeller but nothing obvious was found. The 
vessel remained in Aberdeen overnight for consultation with RVS. The divers 
returned at 0800A (3rd) to inspect the bilge keels but again nothing untoward 
was found. The vessel sailed at 1030A and conducted sea trials off Aberdeen. 
The severe vibration and noise reappeared when the rudder was put hard over at 
l2kts. RVS were informed and the vessel headed south towards Leith which was 
the nearest available drydock We were informed in the afternoon that the Leith 
drydock was not available and that we should head for the Tyne.

The Tyne pilot boarded at 1000A 3rd (184) and the vessel arrived in dry dock in 
Wallsend at noon. The dock was pumped out by 1600 and tests on the rudder were 
carried out. These identified slack in the lower pintle bush and work was 
commenced to rectify the matter.

The vessel remained in dock throughout the 4th and 5th with the ship's 
personnel remaining on board. Repairs to the rudder were almost completed by 
evening of 6th. The vessel sailed at 1400A 7th (188) but took a long time to 
clear dock as she became stuck across the dock entrance on the flooding tide. 
We cleared the mouth of Tyne by 1545A and retried the same helm-hard-over 
manoeuvres as before. The noise and vibration were still present.

The vessel returned to dry dock after Paul Stone (RVS Engineering 
Superintendent) and the dock manager had joined the ship by pilot boat to 
witness the problem at first hand.

Suspicion now fell on the skeg which attaches the propeller rope guard to the 
shell plating. Some minor cracking and rust streaks had been noticed around 
that area. The vessel returned to port and was alongside the drydock by 2330A.

The vessel entered drydock again at 1500 8th (189) and when the dock had been 
drained it was found that the rope guard could indeed vibrate and hit rudder. 
Work was commenced to remove the guard and repair the cracks.

After telephone discussions on the morning of the 9th with Trevor Guymer 
(Acting Head Marine Physics), Peter Saunders and Colin Summerhayes it was 
agreed that a cruise extension would be impracticable due to fact that most of 
officers were due to change at end of the present cruise.

Repair work continued throughout the night and the vessel sailed at 1630A after 
a number of pinhole leaks in the skeg had been welded and the skeg integrity 
tested. The breakwater was cleared by 1800A and course set northwards. High 
speed manoeuvres produced some noise but the previous problems appeared to have 
been largely solved. Passage continued northwards at 12.5 kts.

An Inmarsat message was received from Hendrik van Aken on R/V Tyro. They had 
been delayed through bad weather and would not complete WOCE section AR7 to 
Greenland.

Passage continued northwards throughout July 10th (191) in stiff northerly 
winds. The vessel arrived in the Pentland Firth 1630A and encountered heavy 
swell. This rapidly abated. At 1800A the PES fish was deployed. At 1820A an 
ADCP calibration run at 10 kts was started on courses 000 and 270. This 
continued until 2100A when the GPS satellite constellation reduced from 4 to 2.

The wind increased to F8 overnight 10th/11th with a heavy beam sea. Clocks were 
retarded 1 hr to GMT at midnight. The vessel arrived on station 0500Z/11th 
(192) and after a wire test of two double acoustic release units, CTD CD50001 
was worked to 1170m in centre of Faroe Shetland Channel. All 12 multisampler 
bottles were fired at the bottom, All closed but two thermometer lanyards 
caught up. (We later discovered that we were fixing the thermometer lanyards in 
the wrong place).

The CTD package handled well despite the heavy sea and swell and 35 kt winds. 
We remained on station while the water sampling was completed. The CTD 
conductivity sensor seemed very noisy and with a large offset and so it was 
changed before the next station.

An attempt was made to get the XBT system working but there appeared to be 
water in the launcher cable and in any case it was at that stage too dangerous 
to go out on deck and launch probes.

Course was set towards the start of a section across the Iceland Basin but the 
heavy seas prevented speeds in excess of 5 kts.

The wind abated overnight 11/12th but the heavy swell kept speeds to 8kts. The 
vessel stopped at 1130Z to do wire tests of releases (2 dips) in the gap 
between Bailey and Lousy Banks. These were completed by 1530 and course set for 
start of CTD section.

The CTD section (CD50002-020) was started at 1900Z. The CTD package proved easy 
to handle with the new steadying roller on the A frame. On CD50007 the PS2 data 
stream hung up on the down cast. The CTD was raised and lowered again to cover 
the missing data.

The PSO talked to Tom Hopkins on R/V Alliance at 1645Z 13th (194). Alliance had 
deployed two moorings on the Iceland Faroes Ridge. A regular radio schedule was 
then established with Alliance at 1100Z each day.

In working up the ADCP calibration run a fault was found with the gyro 
interface box. It was found to miss a bit and put directions passing through 
north as 180.

On 14th (195) the vessel stopped at 0030Z for wire tests of releases in 2200m 
of water at the position of CD50012. Two lowerings were completed by 0530Z.

On station CD50014 the CTD connecting wire snagged under the shackle pin as the 
CTD was being lifted from the deck and broke the conductor. While the 
termination was being remade four more acoustic releases were tested to 1200m.

The section continued up the slope south of Iceland. Station CD50018 (in about 
1300m) was found to be downslope of a 50m deep channel. It was decided to do 
CD50019 in the channel but no anomalously cold water was found. The final CTD 
of the section, CD50020, in 700m was worked on the morning of 15th (196).

During the day of the 15th moorings B,C,D,E and F were deployed along the CTD 
line just occupied. (Details are in the mooring section and table.) Passage 
between moorings was slow (? kts) due to fog. The fog cleared at 1330 leaving a 
bright clear sunny day with southerly winds. Mooring deployment continued 
through the day until 2200Z with the deployment of mooring F. This last station 
was delayed somewhat by a hydraulic hose blowing out on the reeler of the 
double barreled mooring capstan. Overnight 15/16th the first station CD50021 of 
a line across the Iceland-Faroes Ridge was worked.

By 0500Z/16th the ship was in position to deploy mooring A. The vessel remained 
at this position to record a longer series of ADCP data and mooring deployment 
started at 0800Z. Mooring C. the last one was completed by 1100Z.

Course was then set for the next CTD of the line (CD50022). CTDs then continued 
with XBT probes in-between. The termination of the CTD wire failed at CD50023 
and had to be replaced before we proceeded. CTD stations continued throughout 
16th (197) and into 17th (198).

The surface expression of the Iceland-Faroes front was crossed ca 1500z 17th. 
We encountered fog as we got towards the front.

The CTD section continued with adjustment of positions on the last two stations 
to get a better distribution of depths.

On completion of the CTDs the vessel ran south to the position on the Iceland 
Faroes ridge for the deployment of the ADCP mooring. The vessel arrived there 
at 1530Z/18th (199) in thick fog. The sea surface temperature there was very 
cold (5.5C). The mooring was deployed uneventfully by 1600Z. The vessel then 
remained in position to see the acoustic releases time out and to await good 
GPS coverage for fixing.

At 1700Z radio contact was made with Hopkins on Alliance and arranged a 
rendezvous arranged for a CTD intercomparison on 64N. Prior to this a short CTD 
section of 5 stations CD50038-042 was worked to look for water which might have 
overtopped the ridge close to the ADCP mooring. The section was completed by 
2330Z/18th (199) and course set to rendezvous with Alliance.

We worked a station within 3 cables of Alliance (CTD50043) 0140-0200Z/19th(200) 
in 490m of water. Visibility was poor (0.5 miles) and deteriorated further as 
we set course for the next CTD section. The fog eventually cleared and the CTD 
section across the continental slope south of Iceland was started at 0830Z/19th 
with XBTs between the first three stations. The section continued through the 
day in good clear weather. Some problems were encountered with the CTD deck 
unit hanging up when bottles were fired at the bottom of the cast. The section 
was completed by midnight.

A series of T7 XBT drops at half-hourly intervals was then started along the 
700m depth contour on the south slope of the Iceland Faroes Ridge running 
towards the Faroe Bank Channel. This was completed by mid morning 20th (201) 
and then course was set towards a repeat of Saunders line Q from Charles Darwin 
Cr42.

Time was by now running short and the shallowest station of the line was 
omitted. There was insufficient time also for the last/deepest station and 
instead of this the last two T5 XBTs were deployed. The section was completed 
by 2000Z 20th (201) and course set for the Pentland Firth.

Passage continued throughout the 21st in good weather. A further ADCP 
calibration run was performed west of Orkney during a period of good GPS data. 
The PES was recovered and course resumed towards Aberdeen.

The vessel docked in Aberdeen 0930A/22nd(203). The following day was spent with 
a film crew from Shell producing footage for a film on Climate Change.

                                                                            WJG
  

  


REPORTS OF SCIENTIFIC WORK.

CTD Operations

During RRS Charles Darwin Cr50, a total of 57 CTD stations were worked

This was the first cruise on which the new Neil Brown CTD deck units and 
Rosette Multisampler deck units were used. A new 10 litre 24 bottle Rosette 
Muitisampler was employed throughout the cruise but with only 12 bottles in 
alternate positions around the rosette.

The total package was made up of a NBIS MkllI CTD with dissolved oxygen sensor 
and a 1m path length transmissometer. These were mounted horizontally in a 
protective frame below the rosette. A 10kHz pinger with tilt indicator was 
mounted in the CTD frame.

The horizontal attitude of the CTD made it extremely easy to mount and service. 
Two lead weights of approximately 40kgs each were secured to the frame to help 
overcome the drag of the rather large package.

Although the package is large, in use it proved very easy to handle. The 12 10-
litre water bottles were used for most of the casts, These were mounted at 
alternate positions around the frame to provide a balanced package.

7 SIS digital reversing thermometers and 2 reversing pressure meters were used 
with the bottles.

The pairing of thermometers was changed on a number of occasions, in order to 
determine calibration errors. (See separate section)

Water sampling was carried out on deck with the bottles mounted permanently on 
the Multisampler.

During the first cast it became apparent that there was a serious problem with 
the conductivity cell. It was not clear if the problem was one of fouling or 
just failure. A new cell was fitted for the remaining casts.

The new deck units and acquisition software generally worked extremely well and 
were easy to use. However, there was a problem on a number of occasions with 
the system crashing alter the start of an upcast when trying to fire the first 
water bottle. It was believed to occur when bottles were fired too soon after 
the end of the down cast. Due to the method used to save the raw data, none 
were lost on these occasions.
  
The CTD and transmissometer worked throughout the cruise without fault. The 
pinger tilt indicators showed that the package rotates slowly during the cast 
but this did not create any problems.

The new articulated arrangement of the CTD A frame made handling the package 
both easy and safe, although weather conditions were never bad enough to really 
test the system. Cable loading on the 8 mm CTD wire could be a problem with the 
ship heaving in heavy seas.

The sea cable had to be reterminated twice during the cruise due to its 
snagging on the shackle at the top of the CTD.

The bottle files generated by the PS2 system were copied to disk and merged 
with sampled salinity and nutrient data on the Sun workstation.

After problems on the first station the stability of the replacement 
conductivity cell was found to be very good, providing an excellent set of data 
for the cruise. The high quality of the calibrations obtained were believed to 
be due to a combination of good sampling technique, the use of new salinity 
sample bottles and the new 10-litre water bottles.

CTD stations are listed on Table 1.

                                                                             JS





Water Sampling and Salinities

Both IOS Guildline salinometers, the new and the old, were carried on this 
cruise in the Charles Darwin's constant temperature laboratory set at 20C with 
salinometers set to run at 21C. Both were kept up and running, but almost all 
sample processing was carried out on the old one, as the new one gave 
indications of instability at the start of the cruise. When work commenced, 
time did not permit the further investigation of this indication. A few checks 
suggested that the new one was working at least adequately, but I am not yet 
confident that it is as reliable as the old machine, which performed 
excellently, being in nearly continuous use for ten days and only wandering 
twice.

A total of 981 samples were processed, comprising 430 duplicate pairs of bottle 
samples, 72 single bottle samples and 49 surface samples from the non-toxic 
supply. Reproducibility between duplicates was of a high standard, with 202 
pairs 0.000 different in salinity, 195 pairs 0.001 different, 24 pairs 0.002 
different and 1 pair each at 0.003, 4, 5 and 6. The two worst pairs result from 
the salinometer's two wanderings.
  
I believe the quality of these results to be due to three things. Firstly, the 
increased frequency of standardisation: once every twelve samples (start, 
middle and end for a crate of 24 samples); secondly, the ten-litre GO bottles, 
being of large volume, make the sample water less susceptible to contamination 
from leaks; and thirdly, the new sample bottles. It is surprising that, 
considering their cheapness (79 pence per bottle), they have not been replaced 
earlier and more often. The old bottles with their onepiece tops were 
contaminated and deteriorating. The new bottles are of fine clear glass with 
disposable stoppers (3 pence each), ensuring a clean seal with no need to worry 
about cap contamination from previous samples. Unfortunately some stoppers had 
to be re-used, as adequate supplies were not available for this cruise. None 
was used more than twice on this cruise. They should be disposed of upon return 
and a large (ca 10,000) supply purchased soon.

Sampling was carried out on deck. A bonus from this which excluded further 
contamination was that the sample bottles were kept in the wet lab, separate 
from the GO bottles, so that they were not swimming in the spill water from the 
GO bottles as they would have been had the old fiddle been used. Sample bottles 
should be kept separate from GO bottles at all times to improve cleanliness. 
Furthermore, upon return, all used sample bottles will be washed clean and 
dried. Storing them with seawater inside for the best part of each year can 
only hasten deterioration and increase the risk of contamination.

With regard to standardisation, 130 ampoules of Standard Seawater batch P113 
were consumed on this cruise. Some defects in the SSW must be noted here.

  i.  Three ampoules were seen to contain floaters, small specks of foreign 
      matter, one seen after opening but two before.

 ii.  One ampoule had not been sealed correctly; upon opening one end, the 
      water poured out of the other.

iii.  Most worryingly, two standards were found which were way off salinity. 
      P113 has Kl5 = 0.99984, i.e. a Guildline ratio of 1.99968. The old 
      salinometer was set to read SSW at or about this value, with drifts 
      typically of ± 0.00010. The two suspect ampoules gave ratios of 1.99999 
      and 2.00050, both confirmed as wrong by immediate re-standardisation.

The changes in standardisation throughout the cruise are presented in fig. 1.
  
It is to be hoped that noted drifts were due to the salinometers, and not to 
less extremely erroneous SSW. It may be possible to use the duplicates as a 
check on the standardisation. This will be attempted in the near future.

Salinity determination from Guildine ratio was performed on the cruise using 
Ocean Scientific International's software package "Salinity". An IBM PS/2 was 
used to run the package.

                                                                             SB





Nutrient Determinations

Analyses for silicate, nitrate and phosphate were carried out on CTD water 
bottle samples from Stations CD50001 to CD50053 on the Alpkem RFA 300 
autoanalyser and Stations CD50001 to CD50057 on the IOSDL autoanalyser. Some 
samples were frozen for later comparison in the lab.

The IOSDL system worked well throughout the cruise, and we expect the primary 
nutrient data to be from this system. The majority of problems experienced 
using the Alpkem were caused by the lack of a manual for the software. Using 
the Help screens it was finally possible to process the data collected.

Nitrate:   comparing the two systems the results agreed to within ± 1%. The 
           Alpkem system worked well, especially the new type of open tube 
           cadmium reducing reactor which needed very little attention.

Silicate:  Comparing results between the two analysers the results were 3-5% 
           different.

Phosphate: The phosphate channel on the Alpkem was not satisfactory due to 
           problems with noise on the signal, possibly caused by the tubing or 
           bubbles, the latter could be improved by inserting a de-bubbler 
           before the flow-cell. The other main problem with the phosphate was 
           drift in the baseline.

There are still some features of the system not tried out, e.g. carry over 
corrections from one sample to the next. The phosphate channel needs to be 
improved and then the Alpkem will be a good system to use at sea, as each 
sample uses 2m1 of seawater and only takes 70s to sample.

                                                                         Jill S
  




Oxygen Determinations

During Cruise 50 it was intended to perform an intercomparison study between 
oxygen titration equipment supplied by UCNW Bangor and a new fully automatic 
unit recently purchased by IOSDL Marine Physics.

Due to a fault with the stabilised power unit, it was not possible to obtain 
results from the UCNW equipment.

The results obtained from the Marine Physics unit were on the whole good. Some 
problems were experienced with air locks trapped in the burette system which 
appeared to be due to a faulty seal. With practice it should be possible to 
reproduce results to a precision of 0.05%, which would be adequate to meet WOCE 
standards and allow comparison between data sets.

The equipment accuracy has also been improved since, supplied with a standard 
of known concentration, the unit will calculate the titre normality and so 
eliminate inaccuracies in calculation due to preparation of solutions.

500 samples were taken during the cruise and analysed in duplicate. The 
preparation and analysis time is rather long and the software supplied with the 
unit has space for only 100 sample bottle volumes. It was therefore only 
possible to have four sets of samples awaiting analysis. With the high 
frequency of CTD sampling it was difficult to maintain a supply of clean 
bottles.

The procedure should be improved by adjusting the software to accommodate a 
larger bottle bank and obtaining more sample bottles.

                                                                             RP





Aluminum Determinations

Dissolved aluminum concentrations are higher in deep waters than in 
intermediate waters. The source of this aluminum has not yet been identified. 
One proposed mechanism has been the dissolution of aluminum from particulate 
aluminosilicate material resuspended into waters containing low concentrations 
of dissolved silica in areas of strong bottom currents such as those 

encountered on this cruise. Aluminum has also been suggested to be a useful 
identifier of water masses giving additional information to that which can be 
gained from the traditional measurements of temperature and salinity and from 
nutrient determinations. The analysis of the results from the detailed sampling 
carried out on this cruise will allow us to determine if aluminum is a useful 
tracer of high latitude water masses.
  
Aluminum determinations were made on 357 samples of unfiltered water out of a 
total of 499 water samples collected on the cruise. 65 determinations were also 
made on samples filtered through 0.2 micron pore size filters.

The concentrations measured ranged from 75nM in unfiltered deep waters with 
high particle concentrations to 2nM in biologically depleted surface waters. 
The precision of the analyses was good on this cruise being consistently better 
than 0.5nM.

Concentrations are higher in the Norwegian Sea than in the Iceland Basin at 
1000m water depth. Contouring of the concentrations shows a distribution that 
follows the density distribution across the Icelandfaroes Ridge. Concentrations 
in the Iceland Basin correspond closely with those determined at the Southern 
end of this basin on the BOFS3 cruise in 1989. Dissolved concentrations are 
markedly higher in waters with high suspended matter concentrations in deep 
water. However the suspended matter in these waters contains aluminum which is 
detected by the fluorometric determination used. (This is not the case in 
surface waters with high suspended matter concentrations, and most previously 
reported determinations of aluminum in deep sea waters have been done on 
unfiltered samples). The aluminum concentration increases more rapidly close to 
the bottom than does the silica concentration. This suggests that there is some 
dissolution of aluminum taking place in the nepheloid layer rather than the 
increase being due to a change in the identity of the water mass.

                                                                            DJH





Digital Reversing Thermometers

The SIS digital reversing thermometers and pressure meters were paired on four 
of the twelve bottles used. For the most part there were pressure 
determinations at the maximum depths reached and temperatures determined at the 
top, bottom and two intermediate depths. Pairings of thermometers were changed 
throughout the cruise to enable intercomparisons to be made. The levels chosen 
for firing the bottles tended to be selected on the basis of providing good 
vertical distributions of nutrient data rather than for being in areas of low 
vertical temperature gradient.

Table 2 shows difference between pairs of digital thermometers, corrected using 
the manufacturer's calibration data. Only 3 pairings show offsets significantly 
different from zero (401-220, 400-220, 238-204). Comparisons with data from 
other pairs does not allow one to conclude that any particular thermometer 
calibration is in error but suspicion falls on 220 and 204.
  
Table 4 shows the difference between the pressure meters and the CTD. 204 shows 
a large but not statistically significant offset, as also do 398 and 401. Again 
thermometer errors cannot be unambiguously identified.

Table 4 shows the difference between the pressure meters and the CTD. These in 
each case demonstrate a pressure (or possibly temperature) dependence.

                                                                        WJG, MW





XBT Measurements

The cruise was the first on which the Hydrographic department's XBT system was 
used. It consists of a Bathysystems SA810 XBT unit interfaced to a Zenith 
personal computer and with a satellite data link to the Meteosat satellite,

The recording unit was installed in the plot, abaft the bridge, and 
communication between the plot and the afterdeck was by means of portable VHF 
sets. This proved less than satisfactory since there were a number of dead 
spots in the plot from which communication was difficult. The recorder was 
connected to a Plessey plug mourned on the after external bulkhead of the main 
lab. Initially there were a number of probes which failed to record good data 
due to an apparent earth leak on the hand held launcher. After this had been 
replaced there were few failures. We noted a number of problems with the XBT 
software:

The timeout period between setting up the recording unit and having to launch a 
probe is too short for a vessel on which the recorder and launcher are so far 
from one another.

More seriously the algorithm for coding the JJXX satellite message ignores 
information input to the program which specifies a depth at which the probe hit 
bottom and below which date are in error. This resulted in apparently subbottom 
data with spurious temperatures being transmitted.

Towards the end of the cruise a considerable number of probes were dropped 
close to the 700m contour on the south side of the Iceland Faroes Ridge. A 
comparison of indicated bottom depth from the XBTs (Plessey T7s) and the 
corrected depth determined from the echo sounder showed that the XBT depths 
were shallow by 37.4±6.6m. An analysis of the data for probes used in shallower 
water depths suggests that a linear relationship between zero error at the 
surface and 40m at 700m would nowhere be in error by more than ±10m. In all 
cases probes were dropped with the ship speed between 8 and 12 kts.
 
Details of all XBT drops are given in Table 5; Fig. 2 shows the observed depth 
errors.
                                                                            WJG





Ship Mounted ADCP

A vessel mounted ADCP (RDI 150kHz) was run between 1800Z/181 and 1900Z/182 
prior to the rudder repairs and from 1753A/190 until 2359Z/202. Three 
configurations were used:

    a)  bottom tracking in depths less than 200m
    b)  bottom tracking in depths to 800m
    c)  water tracking

During the cruise regular notes were made of clock error with respect to the 
vessel's master clock. The ADCP clock was reset every 2.5 days (approx) when 
the error reached of order 1 minute. Checks of the ADCP temperature against the 
ship's hull temperature sensor showed there to be good agreement. Checks were 
also made against the ship's gyro-compass. Heading differences of 1 or 2 
degrees were seen at times.

Data were collected in 2 minute ensembles, transferred in 24 hr segments to RVS 
data flies and thence into the Sun Pstar system. At this stage a number of 
operations were carried out on the data:

    a)  water track and bottom track segments were separated
    b)  velocity units were converted to cm/s
    c)  header information was input
    d)  times were corrected for clock error and converted to seconds
    e)  missing data values were converted from 1999 to -999
    f)  data with % good less than 25% were set to absent data
    g)  the data were corrected with a pointing angle and scaling factor.

These last corrections were derived from calibration runs carried out using the 
method of Read and Pollard (see narrative section). The two calibration 
exercises produced rather different and noisy values for A and phi as follows:
  
    Day 191    A = 1.011 Phi = 0.652
    Day 202    A = 1.122 Phi = 0.016

When the vessel was on station during CTDs, wire tests and mooring deployments, 
time series of data were identified and plotted. It had been hoped to collect 
ADCP data on station and over complete tidal cycles near temporarily deployed 
current meter moorings, but the loss of time with rudder problems precluded 
this. All data files were archived for later processing at IOSDL.

                                                                             KM





Mooring Operations

Seven current meter moorings with 13 Aanderaa current meters were deployed S.E. 
of Iceland for a period of one year in water depths ranging from 1027-2305m. 
The mooring positions were in deeper water than had been planned in light of 
the results from a CTD survey to detect the cold water overflow.

An Acoustic Doppler Current Profiler (ADCP) mooring was deployed at 64 23.8N, 
11 55.7W, which is to be recovered on Charles Darwin 51.

All Aanderaa current meters had been overhauled and calibrated at IOSDL prior 
to the cruise and cold tests carried out to ensure correct operation at 
expected working temperatures. Fins were overhauled and fitted with titanium 
spindle assemblies in an attempt to overcome corrosion problems experienced 
during previous one yearlong deployments. The ADCP and 54 current meter were 
provided by RVS and were already prepared and working when received.

Mooring deployments were carried out using the RVS portable double barrel 
capstan (DBC) winch with the line leading over a snatch block attached to the 
hook on the starboard Effer crane. The Effer cranes on the stem are a recent 
addition to the Charles Darwin and provide an excellent alternative to the A 
frame for mooring deployment/recoveries. A length of 13mm chain was also 
attached to the hook to "stop off" the mooring line as required.

The Aanderaa current meter moorings were all deployed anchor first and the line 
stopped off as required for instrument insertion. Difficulties were experienced 
with the haul/veer control on the DEC when minor adjustments were required but 
generally all deployments were straightforward. It is recommended that in 
future the DEC drums should not be painted so as to improve traction.
  
The ADCP mooring was deployed ADCP first, the method dictated by the 
construction of the buoyancy package. All lines and instruments were 
preassembled on deck prior to deployment, with the release and Aanderaa current 
meter suspended from the block and secured by the line to the DBC. The ADCP and 
S4 current meter were lowered to the waterline on the port Rexroth winch, cut 
away and allowed to drift astern as the ship increased speed to 1.52 knots. The 
glass spheres were lowered by hand as the line tightened and the tension was 
finally taken by the DBC, allowing the release and current meter to be lowered 
away. Finally the anchor was fitted and cut away at the waterline.

Mooring details are given in table 6.

                                                                             KG





Mooring Acoustics

Seven moorings were to be deployed for at least one year. Over the last fifteen 
years about one long term mooring a year has 'vanished', that is, no acoustic 
contact has been made with the acoustic release and relocation unit. In view of 
this and the age of current release stocks, one third over eight years old and 
one third brand new, I decided to double up acoustic units on each mooring. The 
proposed mooring depths ranged smoothly from 200 metres to 2350 metres and so I 
planned to deploy four pairs using 'shallow ceramic ring' acoustic transducers 
and three pairs using 'deep mushroom' acoustic transducers. The physical 
oceanography of the area dictated a last minute change of plan to a deeper 
deployment pattern. With no time to prepare extra deep units I altered the 
pairings so that two of the moorings that were marginal for shallow transducers 
were covered by a transducer of each type.

My original intention of using transponders to mark two of the moorings was 
frustrated by the destruction of one set of electronics by a faulty lithium 
cell. This is the second known failure of a cell of this type (Crompton 
Parkinson 020) in recent months. It is particularly worrying as this cell is 
used in the acoustic release battery pack although no known failures have 
occurred in the ten years we have been using them in that application

A short term (four to six weeks) deployment of a mooring carrying an acoustic 
doppler current meter, an electromagnetic current meter, and a conventional 
rotor current meter was proposed. As the total value of this rig was about 
£100,000 I decided to pair both the IOS type acoustic units provided by RVS for 
this mooring. On inspection of the electronics it was obvious that neither unit 
had been adjusted from new. Both units required significant adjustment before I 
was happy to deploy them.
  
A very short term mooring (multiple deployments of 12 to 14 hours) was proposed 
This was covered by the spare units prepared and tested for the long term 
moorings.

The acoustic units were wire tested at about their proposed operating depth and 
temperature in groups of four on six deployments. One new unit required three 
tests before I was happy with it, five other units required a second test after 
adjustment.

All releases were fitted with two pyroleases.

                                                                             GP





Simrad Precision Echosounder

This unit was run throughout the cruise mainly in a passive 'Pinger' mode using 
the hull mounted acoustic transducer. I will be reviewing the system further on 
Discovery Cruise 194; these are my impressions so far.

Generally the three parameters controlling receiver gain are far 100 complex; 
two of them could be locked to maximum values for most cruises and gain 
controlled in simple 3db steps using the third. I have not yet played with the 
external triggering mode.

1. As a passive monitor it worked well. The ability to use either the VDU or 
   the printer as an expanded window is potentially very useful.

   There are two major drawbacks:

    a) The scale the output is drawn on both VDU and printer is not controlled 
       by the input sound velocity profile as far as I can see. They both 
       appear to be scaled to the default 1472 metres per second  this is not 
       acceptable.
    b) The signal appears to be sampled only one in seven sweeps; that is two 
       seconds in every fourteen. This is unacceptable for most monitoring 
       work, particularly close bottom approach work.

2. As an echosounder also monitoring pingers - essential for all bottom and near 
   bottom approach work it's sophistication is it's downfall.

   a) It can be made to repeat at a precision rate but this involves setting a 
      rate longer than the expected bottom reply. In deep water this can be ten 
      seconds so setting a two second window to monitor a pinger with 
      reasonable resolution involves only sampling one sweep in five - this is 
      unacceptable,
   b) If the software detects a signal of similar amplitude to the expected 
      bottom echo it spends time analysing it and then locks on to it's 
      preferred source. During this time it loses it's precision timing and so 
      all signals are scrambled - this is unacceptable. When it relocks it 
      starts a new sequence so all pinger signals are displaced. It will also 
      then track the pinger signal as the depth so the digital reading will be 
      wrong although the true bottom echo will be obvious to the observer and 
      readable from the scale lines. The resolution readable to the unaided eye 
      on a 1500 metre display is 10 metres at best - this is not really 
      acceptable.
   c) Removal of TVG from echosounding mode appears to have resulted in a 
      monochrome (red) display. This reduces the dynamic range of the display 
      and therefore an easy to use gain control is required.

                                                                             GP





Level A/B/C computing

Data were logged from the following systems:

Em log       - no problems.

Gyro         - when sailing north the synchro output from the gyro produced 
               spurious readings when swinging from 0 to 360 degrees and back 
               It is thought that the stators need adjusting or cleaning. This 
               will have to wait until suitably skilled staff can attend the 
               vessel.

MX1107       - no problems although it was noticed that the bridge officers 
               frequently relied on the MX1107 in preference to the OPS. The 
               provision of a Navigation Display Unit for the GPS is needed 
               particularly now cover is improving.

GPS          - North of about 60N GPS gives almost continuous cover with 3 or 
               more satellites in view for all but two short periods each day. 
               Statistical analysis of GPS data from periods in port have 
               revealed that despite the rubidium frequency standard, fixes 
               derived from 2 satellites are significantly worse than those 
               derived from 3 or more satellites. The degradation now applied 
               to the (PS data gives typical errors of about 45m. in latitude 
               and 95m. in longitude.
               
               The Level A itself developed a fault on the local terminal 
               output and this, together with the occasional spontaneous reset, 
               may mean it is prudent to replace the hardware for the next 
               cruise.

TSG103       - no problems.

CTD          - no problems.

ADCP         - Logged directly into the parser SUN 3/60. This suffered from the 
               same synchro gyro problem mentioned above.

Plot Network - (Cambridge Ring) Server.

               This has an intermittent fault that has as yet not been traced. 
               There is a spare available for the next cruise.

Level B      - performed well with no crashes.

               There were no problems with the level C but some of the ASCII 
               terminals are showing symptoms of age. The bulk of the 
               processing was done in Pstar. The transfer between RVS data file 
               and Pstar (datapup) was initially a problem but advice from 
               colleagues on Discovery during a routine radio schedule solved 
               most of the difficulties.

                                                                            RBL





PSTAR Data Processing

The on board Sun Microsystem network was loaded with the Pstar library which 
was compiled and used successfully throughout the cruise.

The problems encountered on Discovery 189 with tape archiving were not present 
and around 200Mb of data have been archived to tape and brought back to IOSDL.

The RVS program DATAPUP caused some difficulties. The program transfers data 
from RVS level C to IOSDL Pstar format. The problem arose when a file was left 
open after being written to by an instrument. It was assumed that in leaving 
the file open the file pointer was not sure of its exact position and so 
transferred no data. When files were closed after being written to the problem 
disappeared.

The processing of CTD data from the 57 stations on Darwin 50 was similar to 
that used on Discovery 189. Differences in processing were mainly caused by the 
introduction of the new CTD deck unit which made part of the old data route redundant.

The processing was therefore mainly accomplished using the existing execs (an 
exec is a collection of Pstar programs that run together in sequence).

CTDEXEC0  reads in the data from an RVS file. This sometimes caused problems 
          from the program datapup.
CTDEXEC1  performed a calibration on the data. Three calibration files were 
          used throughout the cruise with modifications being made to the 
          pressure and conductivity calibration values.
CTDEXEC2  was used to extract the down cast from the ctd station.
CTDEXEC5  was modified to produce less derived variables and averaged the data 
          on 2db intervals.

Considerable time was spent on working through the method used on Discovery 189 
(CTDEXEC4) to correct the salinity values but because of time restrictions this 
was left until the return to IOSDL. Potential temperature against salinity was 
plotted for each CTD station. The data was gridded and plotted in sections for 
temperature, salinity and sigma. The sections were plotted out as below.

                                Calibration 
                      Stations    file no.   No of stations
                      --------  -----------  --------------
                      CD50001        1              1
                      002-020        1             19
                      021-037        1             17
                      038-042        2              5
                      043            2              1
                      044-053        3             10
                      054-057        3              4


The data were archived all the way through the process. The full data 
processing route for each station is as below:

                      CTDEXEC0  
                                             archived copy 
                      CTDEXEC1  
                                             archived copy
                      CTDEXEC2  
                                             archived copy
                      CTDEXEC5  
                                             archived copy 
                      gridded into sections  
                      

The method used on Darwin 50 for the display of nutrient data is different to 
that used on any previous cruise mainly because of the introduction of the new 
CTD deck unit.

For each CTD cast the deck unit creates a "bottle" file. This file contains a 
header. The header contains a unique label for each CTD station, the 
geographical position and the time of the cast. The file also contains CTD data 
from each of the sensors averaged about the time at which a bottle was fired. 
It has one such line for each bottle firing. For example in normal use the 
bottle file had 24 lines, one for each space in the rosette whether it had a 
bottle in it or not. A misfire when trying to dose a bottle would appear as an 
extra line of data in the bottle file.

Each bottle file was edited using the Sun microsystem screen editor. The header 
was deleted as were any lines of data that did not correspond to a bottle on 
the rosette sampler. The variables that were not used in Darwin 50 (e.g. 
fluorescence) were deleted. There then remained a bottle file that just 
consisted of the following 8 variables

                                     Salinity
                      Bottle number  
                                     Oxygen current 
                      Pressure  
                                     Oxygen temperature 
                      Temperature  
                                     Dissolved oxygen 
                      Conductivity  


The next stage was to bring in the nutrient data, the bottle determined 
salinity and dissolved oxygen. Using the hydrographic log sheets and the unique 
sample number that was used on this cruise for each bottle, it was a simple 
matter to piece the correct sample data to the correct line in a bottle file 
using the basic Sun editor facilities (cut, copy, paste)

        Each bottle file now contained 16 variables in an ASCII file:
  
        Bottle number                                  Sample number
  
        Pressure                                           Sample O2
  
        Temperature                                  Sample salinity
  
        Conductivity                                        Aluminum
  
        Salinity                                   Filtered aluminum
  
        Oxygen current                                       Nitrate
  
        Oxygen temperature                                 Phosphate
  
        Dissolved oxygen                                    Silicate

This file was read into Pstar format using the Pstar program PASCIN, thus 
creating one Pstar file for each CTD station. Once in this format it was easy 
to grid and plot the nutrient data in a similar form to that used in the CTD 
sections. Although this was a simple part of the processing it was extremely 
time consuming and hopefully the more experienced personnel on Darwin 51 will 
come up with a less time absorbing way of displaying nutrient data.

As the files created using the method above contained a raw conductivity value 
and a bottle salinity value (assumed to be correct), a new value for the 
conductivity could be calculated. This new conductivity value could then be 
divided by the old value to derive a ratio. This ratio is called the corrected 
conductivity ratio and is used in the CTD calibration files (see ctdexec1 ). A 
Pstar program was written to work out this corrected conductivity ratio 
(CRAT.F), and write the results to a file, The file was then analysed by 
calculating a mean and standard deviation of the conductivity ratios to see 

just how the conductivity ratio changes with time. At sea this was only done on 
the first 20 stations, but showed that the previously used conductivity ratio 
of 0.99987 was wrong and a much better value would in fact have been 1.0002. 
The calibration file in CTDEXEC1 was changed on the basis of this result. It 
was felt that the results showed promise but as with the nutrient data the main 
problem was a time consuming method of getting to them.

                                                                            MAB
  

  


ACKNOWLEDGMENTS

This cruise was severely disrupted by problems with the vessel's rudder which 
necessitated three unscheduled port calls and two periods in dry dock; all this 
before any work had been done. It says much for the forbearance of all the 
ship's personnel, scientists, officers and crew that so much was achieved in 
the remaining ten working days.
  

  


                                     TABLE 1

                                CTD Station list

Consec-  Time                               Water  Closest 
utive    Down  Day/Date                     depth  Approach 
Number    z      1990     Lat N    Lon W      m       m     Comments
-------  ----  ---------  -------  -------  -----  -------  ------------------
   1     0845  192(11-7)  60 10.5  6 03.8   1212      33     FS1 All bottles 
                                                             fired at bottom
   2     1940  193(12-7)  60 29.0  12 41.9   405      14     IB1
   3     2118  193(12-7)  60 33.7  12 53.1   602       7     IB2
   4     2319  193(12-7)  60 39.0  13 03.0  1045      16     IB3
   5     0125  194(13-7)  60 44.2  13 13.2  1440      15     IB4
   6     0351  194(13-7)  60 50.3  13 25.8  1667      18     lB5
   7     0627  194(13-7)  60 55.1  13 36.2  1675      10     IB6
   8     1001  194(13-7)  61 07.9  14 06.5  1759       7     IB7 Computer crash 
                                                             on way down   
   9     1355  194(13-7)  61 23.3  14 35.6  2070      15     IB8
  10     1812  194(13-7)  61 36.3  15 6.8   2157       1     IB9
  11     2158  194(13-7)  61 49.7  15 36.1  2290      14     IB10
  12     0714  195(14-7)  62 03.7  16 03.6  2218       8     IB11
  13     1033  195(14-7)  62 17.8  16 18.9  2120      13     IB12
  14     1540  195(14-7)  62 30.0  16 33.7  2065       9     IB13
  15     1825  195(14-7)  62 41.3  16 47.4  1830       8     IB14
  16     2043  195(14-7)  62 48.3  16 54.1  1675       9     IB15
  17     2312  195(14-7)  62 54.0  17 00.9  cal550     9     IB16 depth not 
                                                             observed
  18     0150  196(15-7)  63 00.4  17 08.1  1297      13     IB17
  19     0432  196(15-7)  63 12.6  17 12.6  1322       8     IB18
  20     0714  196(15-7)  63 12.0  17 22.1   660      10     IB19
  21     0020  197(16-7)  62 10.4  15 31.8  2222       8     T1
  22     1425  197(16-7)  62 19.2  15 04.0  2030      12     T2
  23     1827  197(16-7)  62 28.0  14 38.9  1761       8     T3 Second attempt 
                                                             after cable failed
  24     2132  197(16-7)  62 37.9  14 10.1  1465       8     T4
  25     0026  198(17-7)  62 47.0  13 41.6  1120      15     T5
  26     0302  198(17-7)  62 56.6  13 14.3   820       7     T6
  27     0520  198(17-7)  63 05.6  12 46.6   535       6     T7
  28     0723  198(17-7)  63 14.2  12 19.6   435      10     T8
  29     0945  198(17-7)  63 23.1  11 52.0   410       5     T9
  30     1210  198(17-7)  63 33.2  11 24.9   322       7     T10
  31     1412  198(17-7)  63 42.1  10 55.8   385       5     T11
  32     1621  198(17-7)  63 51.5  10 27.0   518       8     T12
  33     1827  198(17-7)  63 59.9  10 00.5   646       8     T13
  34     2043  198(17-7)  64 09.1  09 31.5   890       6     T14
  35     2308  198(17-7)  64 18.3  09 02.6  1010      12     T15 Computer crash 
                                                             at bottom
  36     0143  199(18-7)  64 27.5  08 31.3  1040      12     T16
  37     0415  199(18-7)  64 31.6  08 19.0  2380      10     T17
  38     1840  199(18-7)  64 22.1  12 27.3   243      11     C1
  39     1947  199(18-7)  64 19.3  12 18.7   465       8     C2
  40     2057  199(18-7)  64 16.2  12 10.5   446       7     C3
  41     2213  199(18-7)  64 13.0  12 02.8   425       7     C4
  42     2319  199(18-7)  64 10.0  11 54.6   383       7     C5
  43     0147  200(19-7)  64 01.4  12 24.7   490       7     Alliance 
                                                             intercomparison  
  44     0837  200(19-7)  63 42.9  14 24.0   310       9     O1
  45     0941  200(19-7)  63 42.2  14 22.1   700      10     O2
  46     1121  200(19-7)  63 37.0  14 15.9  1180      14     O3
  47     1315  200(19-7)  63 30.7  14 08.0  1415      10     O4 No O2 samples
  48     1512  200(19-7)  63 25.3  13 59.0  1337       7     O5
  49     1706  200(19-7)  63 19.7  13 49.9  1305       7     O6
  50     1903  200(19-7)  63 14.1  13 41.2  1190       7     O7
  51     2044  200(19-7)  63 08.1  13 32.2  1005       9     O8
  52     2224  200(19-7)  63 02.4  13 23.2   890       8     O9
  53     2359  200(19-7)  62 56.5  13 15.0   825      10     O10 Repeat of T6
  54     1333  201(20-7)  61 53.6  09 05.3   585      10     Q5
  55     1503  201(20-7)  61 48.8  09 16.7   730      12     Q4
  56     1708  201(20-7)  61 43.7  09 26.1   860      10     Q3
  57     1853  201(20-7)  61 38.7  09 36.9  1000      37     Q2 High shear near 
                                                             bottom   

Note depths are as recorded by the ship's PES. Sound speed is assumed at 1500 
m.sec-1.
  

  


                                     TABLE 2

     Differences between pairs of digital reversing thermometers (mK x 1000)

                  Pair of                    Standard  Standard 
               Thermometers  Number  Mean   deviation    Error
               ------------  ------  -----  ---------  --------
                 400-398        7   -0.83     3.4        1.29
                 401-238        9   -0.143    2.27       0.76
                 220-204        7    1        5.35       2.02
                 399-238        7   -1.29     3.73       1.4
                 398-238       14    2.36     2.3        0.61
                 401-220        4    6.25     0.96       0.48
                 401-400       23    1.43     4.98       1.04
                 400-220       15    6.6      3.29       0.85
                 238-204        8    6.25     3.5        1.24
                 399-398        8    0.375    1.92       0.68
                 399-204        8    3.75    10.95       3.87

  



                                     TABLE 3

 Differences between digital reversing thermometers and CTD (DRT-CTD) mK x 1000

                 Number of                           Standard   Standard 
    Thermometer   Samples   Minimum  Maximum   Mean  Deviation   Error
    -----------  ---------  -------  -------  -----  ---------  --------
        204         21        -50       8     -6.63    12.44      2.71
        220         37        -44      43     -0.96    14.7       2.42
        238         33        -60      54     -0.55    22.95      3.98
        398         21          2      44     12.35    11.69      2.55
        399         23        -32      21     -0.99    13.88      2.89
        400         37        -31      31      3.73    10.26      1.69
        401         45         -5      36      6.91     6.23      0.93





                                     TABLE 4

               Differences between CTD and digital pressure meters

           6132H         P<500  500<P<1000  1000<P<1500  P>1500  overall
           mean           0.5      1.4          4.6        7.2     3.2
    standard deviation    2.1      1.6          2.6        0.8     2.0
          number         10       13           14          7      44
                                                               (965 ± 185)

           6075S         P<500  500<P<1000  l000<P<1500  P>1500  overall
           mean          -3.6     -1.1          3.00       2.8     0.7
    standard deviation    2.0      2.6          3.6        6.2     4.0
          number          7       12           12         11      42





                                     TABLE 5

                                XBT Station list

                                                     Max   Water 
     Seq  File                                      Depth  Depth    Probe 
      No   No   Day/Date  Time z  Lat N    Long W     m      m       No
     ---  ----  --------  ------  -------  -------  -----  -----  ---------
       1  test              
       2  test              
       3                    Weight dropped off probe              p1x043441
           73A  192(11-7)  2049   60 19.0  08 00.0   692    740   p1x042444
       4   74a  193(12-7)  0444   60 21.0  09 42.0   ***   1060   p1x043442
       5   75a  193(12-7)  1511   60 26.0  11 27.0   ***   1210   p1x043445
       6   56a            Failed, wire blew onto ship
       7   77a                       Noisy
           77b                       Noisy
           77c            Test probe Changed launcher
       8   58a  197(16-7)  1600  62 23.9  14 51.9    ***   1900    208178
       9   59a  197(16-7)  2002  62 33.4  14 24.4   1645   1628    208185
      10  510a  197(16-7)  2300  62 42.0  13 56.0   1305   1265    208180
      11  511a  198(17-7)  0201  62 53.2  13 25.6    968    955    208188
      12  712a  198(17-7)  0415  63 01.5  12 58.2    612    650   
      13  713a  198(17-7)  0622  63 10.3  12 33.2    440    470   p1x043448
      14                         Failed at 50m
      15   u/s  
      16  716a  198(17-7)  0838  63 18.9  12 02.8    381    410   p1x04377?
      17                          Fouled ship
      18  718a  198(17-7)  1114  62 28.7  11 36.4    352    373   p1x043484
      19  719a  198(17-7)  1315  63 39.3  11 11.1    335    345   p1x043483
      20  720a  198(17-7)  1517  63 46.8  11 40.1    444    465   p1x043481
      21  721a  198(17-7)  1725  63 13.4  10 14.7    540    585   p1x043482
      22  722a                   Suspect data                     plx043478
          722b  198(17-7)  1946  64 04.7  09 45.9           800   p1x043478
      23  523a  198(17-7)  2202  64 14.9  09 14.4    976    975    208189
      24  724a                       Noisy                        p1x043480
          724b  199(18-7)  0024  64 23.1  08 46.9    ***   1090   p1x043485
      25  725a  200(19-7)  0859  63 42.6  14 23.0    462    500   p1x043704
      26  526a  200(19-7)  1013  63 41.5  14 20.5    993    970    208182
      27  727a  201(20-7)  0058  63 00.5  13 04.6    646    700   p1x043703
      28  728a  201(20-7)  0129  62 57.7  12 54.4    617    650   p1x043698
      29  729a  201(20-7)  0159  62 54.2  12 45.4    632    677   p1x043702
      30  730a  201(20-7)  0229  62 51.9  12 35.6    683    696   p1x043701
      31  731a  201(20-7)  0259  62 49.6  12 25.2    652    691   p1x043700
      32  732a  201(20-7)  0329  62 47.2  12 13.5    652    689   p1x043699
      33  733a  201(20-7)  0359  62 44.9  12 02.7    648    694   p1x043690
      34  734a  201(20-7)  0429  62 42.5  11 51.7    651    695   p1x043694
      35  735a  201(20-7)  0500  62 40.1  11 40.6    658    690   p1x043693
      36  736a  201(20-7)  0529  62 37.8  11 29.8    640    687   p1x043443
      37  737a  201(20-7)  0559  62 35.5  11 18.8    654    685   p1x043697
      38  738a  201(20-7)  0629  62 33.1  11 08.0    657    700   p1x043695
      39  739a  201(20-7)  0659  62 30.7  10 56.8    642    685   p1x043562
      40  740a  201(20-7)  0729  62 27.6  10 47.2    640    670   p1x043563
      41  741a  201(20-7)  0759  62 23.7  10 38.9    640    680   p1x043564
      42  742a  201(20-7)  0830  62 19.9  10 30.3    700    745   p1x043572
      43  743a  201(20-7)  0902  62 18.0  10 18.6    736    790   p1x043571
      44  744a  201(20-7)  0930  62 18.3  10 07.0    690    735   p1x043565
      45  745a  201(20-7)  1000  62 17.4  09 55.7    643    685   p1x043568
      46  746a  201(20-7)  1030  62 15.0  09 44.7    615    660   p1x043569
      47  547a  201(20-7)  1940  61 36.3  09 40.3   1060   1038    208181
      48  548a  201(20-7)  2002  61 34.2  09 40.3   1085   1060    208183

Water depth is measured by the ship's PES with an assumed velocity of 1500 m/s. 
*** indicates probe did not hit bottom.
  

  




                                       TABLE 6

                                 Mooring Deployments

(Note... All depths are measured at 1500 m/s and uncorrected for sound speed profile.)


        MOORING A     61 44.3 N   15 23.9 W            2290m       
                      DEPLOYMENT  COMMENCED            0810Z       16/07/90
                                  COMPLETED            0823Z       16/07/90
                                  ON BOTTOM            0837        16/07/90
                      CR 2462                          1.10 314-322/355-362
                      TRANSPONDER                     

                      ACM 7948    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           0812Z       16/07/90
                                  IN WATER             0816Z       16/07/90

        MOORING B     63 08.6 N   17 17.8 W            1027m       
                      DEPLOYMENT  COMMENCED            0833Z       15/07 90
                                  COMPLETED            0848Z       15/07/90
                                  ON BOTTOM            0855Z       15/07/90
                      CR 2512                          1.10 315-320/355-362
                      CR 2523                          1.02 312-325/256-265

                      ACM 3727    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           0841Z       15/07/90
                                  IN WATER             0841Z       15/07/90

        MOORING C     62 59.91 N  17 06.54 W           1300m       
                      DEPLOYMENT  COMMENCED            1044Z       15/07/90
                                  COMPLETED            1055Z       15/07/90
                                  ON BOTTOM            104Z        15/07/90
                      CR 2521                          1.08 313-327/434-449
                      CR 2522                          1.06 312-326/453-467
                      ACM 5205    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           1047Z       15/07/90
                                  IN WATER             1047Z       15/07/90

        MOORING D     62 43.1 N   16 49.2 W            1800m       
                      DEPLOYMENT  COMMENCED            1405Z       15/07/90
                                  COMPLETED            1438Z       15/07/90
                                  ON BOTTOM            1449Z       15/07/90
                                  CR 2520              1.12 316-323/415-424
                                  CR 2400              0.94 312-322/333-343

                      ACM 6867    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           1430Z       15/07/90
                                  N WATER              1433Z       15/07190
                      ACM 3726    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09107/90
                                  ROTOR FREE           14hZ        15/07/90
                                  IN WATER             1433Z       15/07/90
                      ACM 2107    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           1406Z        5/07/90
                                  IN WATER             1410Z       15/07/90

        MOORING E     62 26.3814  16 28.25W            2055m       
                      DEPLOYMENT  COMMENCED            1723Z       15/07/90
                                  COMPLETED            1800Z       15/07/90
                                  ON BOTTOM            1815Z       15/07/90
                      CR 2519                          1.14 314-325/295-305
                      CR 2385                          1.04 314-322/336-345
                      ACM 6225    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           1752Z       15/07/90
                                  IN WATER             1755Z       15/07/90
                      ACM 2108    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           1738Z       15/07/90
                                  IN WATER             1740Z       15/07/90
                      ACM 7945    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           1724Z       15/07/90
                                  IN WATER             1725Z       15/07/90
                                           
        MOORING F     62 03.8N    16 03.3W             2235m       
                      DEPLOYMENT  COMMENCED            2113Z       15/07/90
                                  COMPLETED            2136Z       15/07/90
                                  ON BOTTOM            2154Z       5/07/90
                      CR 2557                          1.00 316-323/453-467
                      CR 2499                          1.12 315-324/374-386

                      ACM 8011    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           2118Z       15/07/90
                                  IN WATER             2132Z       15/07/90
                      ACM 3624    1 HR SAMPLE 8 RPC              
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           2115Z       15/07/90
                                  IN WATER             2118Z       15/07/90

        MOORING G     61 49.914   15 37.4W             2305m  
                      DEPLOYMENT  COMMENCED            1000Z       16/07/90
                                  COMPLETED            1022Z       16/07/90
                                  ON BOTTOM            1043Z       16/07/90
                      CR 282                           1.04 313-322/353-366
                      CR 2417                          1.18 314-326/394-405
                      ACM 2109    1 HR SAMPLE 8 RPC    
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           10101Z      16/07/90
                                  IN WATER             10hZ        16/07/90
                      ACM 4738    1 HR SAMPLE 8 RPC    
                                  1ST DATA             1200Z       09/07/90
                                  ROTOR FREE           0958Z       16/07/90
                                  IN WATER             1005Z       16/07/90

        ADCP MOORING              64 23.8N             11 55.7W    435m
                      DEPLOYMENT  COMMENCED            554Z        18/07/90
                                  COMPLETED            1600Z       18/07/90
                                  ON BOTTOM            1603Z       18/07/90
                      CR 2465                          1.02.316-322/356-362
                      CR 2490                          1.04 317-324/236-243

                      ACM 7401    10 MIN SAMPLE 4 RPC    
                                  1ST DATA             1630Z       17/07/90
                                  ROTOR FREE           1547Z       18/07/90
                                  IN WATER             1600Z       18/07/90
    
      
    
Figure 1: Changes in Salinometer Standardisation during Cruise 50  
Figure 2
Figure 3: RRS Charles Darwin
          Cruise 50 29 Jan - 22 Jul 1990
          Track Chart showing positions of CTD sections



CCHDO Data Processing Notes

Date        Person          Data Type  Action           Summary
----------  --------------  ---------  ---------------  -----------------------
2000-05-11  Gould, W. John  CTD/BTL    Data are Public        

2001-01-16  Holliday, P.    Cruise ID  Website Updated  John Gould was chief 
                                                        scientist for CD50 
            I can confirm that Harry Bryden was chief scientist for DI214 and 
            that John Gould was chief scientist for CD50.

2001-09-07  Uribe, Karla    DOC/SUM    Website Updated  Reformatted data 
                                                        online, moved from NON-
                                                        WHP to AR25 
            The data for this cruise has been copied from NON_WHPO directory 
            under ATLANTIC/1990/74CD50_1. This cruise was placed in the third 
            position (c) of ar25, according to the Mooring chart this is the 
            appropriate line number. Sumfile had extra lines at the top of the 
            file, they were removed and minor reformatting was done, it now 
            pases WHPO tests. The DOC remains in htm format.

2002-03-18  Uribe, Karla     BTL       Website Updated  Exchange file online 
            Bottle file was converted to exchange and put online.  Data checked 
            with JOA, no apparent problems.

2014-10-21  Kappa, Jerry     CrsRpt    Website Updated  PDF version online
            I've placed a new PDF version of the cruise report:  
              74CD50_1do.pdf
            into the directory:     
              http://cchdo.ucsd.edu/data/repeat/atlantic/ar25/ar25_c/ar25_chy.txt 
            It includes all the reports provided by the cruise PIs, summary 
            pages and CCHDO data processing notes, as well as a linked Table of 
            Contents and links to figures, tables and appendices.

