A.     CRUISE NARRATIVE

A.1    HIGHLIGHTS
                        WHP Cruise Summary Information

                 WOCE section designation  AR07E
        Expedition designation (EXPOCODE)  64TR90_3
Chief scientist(s) and their affiliations  Chief Scientist  Dr. Hendrik M. van Aken
                                           NIOZ  PO Box 59
                                           1790AB Den Burg/Texel
                                           the Netherlands
                                           Internet - aken@vortex.nioz.nl
                                           Telemail: NIOZ.TEXEL
                             Cruise Dates  1 July - 23 July, 1990
                                     Ship  R/V TYRO
                            Ports of call  Leg from Galway, Ireland to Reykjavik, Iceland
                       Number of stations  33
                                                  64° N
    Geographic boundaries of the stations  44° W         10° W
                                                  52° N
            Floaters or drifters deployed  0
           Moorings deployed or recovered  1

A.2  Cruise summary

Research was carried out by Scientists and technicians from the Netherlands 
Institute for Sea Research (NIOZ) assisted by students from Utrecht and 
Wageningen.


OBJECTIVE

To contribute to the WOCE Hydrographic Program by carrying out surveys along the Atlantic repeat section AR07E.

To study the deep transport of overflow water from the Faroese regions through the Iceland Basin.

To study the circulation and heat budget of the Atlantic Current in the Northeastern Atlantic Basin.


Cruise Track

Geographic Bounds:

R/V TYRO departed Galway, Ireland on the morning of 1 July 1990, arriving at 
the Porcupine Bank the following morning. From there, on section AR7E, 33 CTD 
(Conductivity, Temperature, and Depth Instrument) stations were occupied, one 
every thirty miles (with an extra station over the steep slope of Porcupine 
Bank). Each CTD station also took water samples with a 24 bottle Rosette 
sampler using 12-liter bottles. Coordinates of station number 1 (rounded to the 
nearest minute) were 52 20N, 14 00W. Track from there was West to 52 20N, 20 
00W, then WNW to 54 20N, 26 00W, then NNW to 60 00N, 29 38W, then slightly 
North of West to the last of the 33 stations at 60 13N, 33 43W. Having lost 98 
hours due to bad weather, it was decided to terminate the AR7E section at 
station 33, about 260 miles from the Greenland coast. This resulted in the loss 
of the westernmost portion of the section, about 20% of the total length.

A.2.a. Underway Measurements 

Ship's position, meteorological data, sea surface parameters, and echo sounder 
depths were recorded continuously during the cruise. The sampling rate of these 
measurements was once per minute. Parameters measured were:

Latitude, Wind Speed, Sea Surface Temperature
Longitude, Wind Direction, Sea Surface Salinity
Speed, Air Temperature, Sea Surface Flourescence
Heading, Relative Humidity, Water Depth
Insolation 

Four times per day, meteorological observations were sent as OBS messages to the GTS network.

After CTD Station No. 9, XBT Profiles were recorded between CTD Stations to 
increase the horizontal resolution of the temperature structure in the upper 
ocean.


A.2.b. Floats and Drifters

Three Argos Drifters were launched. Positions and dates were:

                    Date      Time(UTC)  Latitude     Longitude
                    --------------------------------------------
                    6 Jul 90  1342       53° 19.7' N  22° 57.8' W
                    6 Jul 90  1855       53° 37.0' N  23° 42.4' W
                    7 Jul 90  0017       53° 48.8' N  24° 26.4' W


A.2.c. Current Meter Moorings

One current meter mooring (designated IB90/4) was deployed at 58 45N, 28 40W.

A.2.d. Other Activities

The remainder of this leg of the cruise was spent on non-WOCE activities. Two 
control volumes in the Iceland Basin were surveyed with 15-mile CTD station 
spacing. Three more current meter moorings were deployed and one recovered.

A.2.e.  Principal Investigators/Affiliation

Table 1: Principal Investigators/Affiliation


            Name            Affiliation       Measurement  Responsibility
            -------------------------------------------------------------
            H. M. van Aken  NIOZ              CTD analysis and interpretation,
                                              sample interpretation
            L. Otto         NIOZ              Surface program, salinometry
            M. Stoll        NIOZ              Carbon dioxide
            T. de Bruin     NIOZ              Underway measurements


A.3.   Cruise Personnel

Table 2: Cruise Personnel


   Name              Measurement  Responsibility                  Affiliation
   --------------------------------------------------------------------------
   H. van Aken (PI)  CTD analysis, sample interpretation          NIOZ
   L. Otto (PI)      Surface Program, Salinometry                 NIOZ
   C. de Boer        CTD operations, CTD & sample analysis        NWO/NIOZ
   T. de Bruin       CTD operations, meteorology, remote sensing  BCRS/NIOZ
   M. Stoll (PI)     Carbon dioxide                               NWO/NIOZ
   M. Manuels        Oxygen analysis                              NIOZ
   K. Bakker         Nutrients analysis                           NIOZ
   S. Ober           CTD operations, current meters               NIOZ
   R. X. de Coster   CTD operations, data management              NIOZ
   R. Groenwegen     CTD operations, electronics                  NIOZ
   L. Oost           CTD operations, electronics                  NIOZ
   H. de Porto       CTD winch, moorings                          NIOZ
   W. Polman         CTD winch, moorings                          NIOZ
   J. Blom           CTD winch, moorings                          NIOZ
   M. Bakker         CTD winch, moorings                          NIOZ
   M. Vosbeek        CTD operations, salinometry                  RUU
   M. Vellinga       CTD operations, salinometry                  RUU
   B. de Jong        CTD operations, salinometry                  RUU
   F-P. Lam          CTD operations, salinometry                  RUU
   J. Belgers        Oxygen analysis                              IAHL

Abbreviations  NIOZ  Netherlands Institute for Sea Research
               NWO   Netherlands National Science Foundation
               BCRS  Netherlands Remote Sensing Board
               RUU   Student from Utrecht
               IAHL  Student from Wageningen
               PI    Principal Investigator


C.     SAMPLING METHODOLOGY

C.1.   CTD

The CTD used was a Neil Brown Mk3 with the following sensors: Temperature (fast 
and slow response sensors electronically combined), conductivity sensor, oxygen 
probe, flourometer, and transmissometer. The CTD was mounted in a Rosette 
sampler with 24 twelve-liter Niskin bottles.  No calibration specifications 
were given for the flourometer or transmissometer, nor are the data reported.


PRESSURE

The CTD pressure is checked by comparison with unprotected reversing 
thermometers and SIS electronic pressure sensors. Since 1987, no systematic 
differences with the manufacturerís calibration have been found.

TEMPERATURE

For CTD temperature calibration, readings were compared with data from pairs of 
SIS electronic reversing thermometers (ERT) mounted on Niskin bottles. Bottles 
1, 3, and 5 each had two ERTs mounted. They were calibrated the week before and 
the week after the cruise. The rms difference between a pair of ERTs averaged 
1.8 mK. Data inspection revealed the shallower stations near the Reykjanes 
ridge, which have relatively high gradients in the bottom layer, contributed 
substantially to this value. Removal of all pairs obtained at less than 2500 
dbar lowers the rms difference to 1.3 mK. The standard deviation of differences 
between CTD and ERTs shallower than 2500 dbars is 1.4 mK

SALINITY

Salinity calibration was determined by comparing the salinity of bottle samples 
taken at specific depths on the upcast with corresponding CTD values. Samples 
were analyzed with a Guildline Autosal salinometer referenced to IAPSO standard 
water batch P112. Except for Stations 12 and 13, samples from even numbered 
bottles were analyzed. Stations 12 and 13 had no reliable CTD conductivity 
values because of sensor damage, so all 24 bottles were analyzed for salinity. 
75 duplicates were analyzed. Of these, 58 showed no difference in the 3rd 
decimal place, 15 had differences of .001 psu, and 1 each of .002 and .003 psu.

OXYGEN

Of the 33 AR7E stations, the first eight have no CTD oxygen data, because the 
oxygen sensor failed. Duplicate samples from odd-numbered Niskin bottles on all 
33 casts were analyzed for oxygen concentration using a high precision 
photometric end point determination developed at NIOZ. Discounting outliers, 
(about 1 in every 150), the rms differences between duplicate bottles was 0.5 
µmol/kg.

NUTRIENTS

Nutrient samples from all bottles were analyzed with a Technicon TRAACS 
autoanalyzer set at 60 samples per hour. Variables measured were Phosphate, 
Silicate, Nitrite, and Nitrate.  Numerous duplicate samples were analyzed to 
ensure data consistency, resulting in the following rms differences: Phosphates 
- 0.07 µmol/kg, Silicate - 0.09 µmol/kg, Nitrate - 0.2 µmol/kg. Nitrite rms 
differences were not stated.


CARBIN DIOXIDE

At 13 stations total carbon (TCARBN) was measured using a high-precision 
coulometrics instrument.

HELIUM/TRITIUM

At a limited number of stations water samples were stored for later Tritium 
analysis. These do not appear in the data files. It is suggested that requests 
for these data go to the Chief Scientist.

WHPO SUMMARY

Because a calibration facility is not yet finished, the CTD has had no 
laboratory calibrations since its purchase in 1987. Calibrations are carried 
out in the field. Detailed comparisons with other WOCE data will follow once 
these become available. Comments from the data quality evaluators (DQEs) follow 
below.

SALINITY, OXYGEN, AND NUTRIENTS  
  - David Ellett, Dunstaffnage Marine Laboratory

The data exhibit a high standard of consistency, and salinity, oxygen, and 
silicate results are compatible with previous high quality observations from 
this region and with the perceived water mass structure. Few previous data are 
available in the literature for NE Atlantic nitrate, nitrite, and phosphate, 
and those which exist are not from modern methods of determination, so detailed 
comparison would be inappropriate, but there is good general agreement with 
earlier work in overlapping areas, and the replicate analyses quoted above 
demonstrate that good care has been taken in the determinations.

CTD DATA  
  - James Crease, W.O.C.E. Data Information Unit (DIU)

Histograms of bottle-CTD differences indicate that the data is of high quality 
and meeting the WOCE requirements.... On many stations the Tyro stations went 
beyond the climatology (Levitus) bounds (but marginally), mostly in the upper 
500m. This was always on the colder side of the bounds. The small size of the 
historical database is presumably only part of the reason for this and some 
effect can be ascribed to changes in the climatology.

Chief Scientist's response to DQE Comments:

From the other non-WOCE sections surveyed during the cruise it appears that the 
mode water, found in the upper 500 m shows some spatial variation in 
temperature and salinity in the Iceland Basin. Therefore I don't know whether 
the differences have to be ascribed to climatic changes or to under-sampling in 
the Levitus data set.

DATA LOCATION

Quality evaluated CTD and bottle data sets are available from the anonymous ftp 
server at the SAC and from WDC-A/NODC.

ACKNOWLEDGEMENTS

This research on board Tyro was carried out by scientists and technicians 
employed by the Netherlands Institute for Sea Research (NIOZ) in Texel assisted 
by students from Utrecht and Wageningen. Additional funding was obtained from 
the  Netherlands Marine Research foundation (SOZ), the owner of the R/V Tyro, 
from the Netherlands National Science Foundation (NWO) and from the Netherlands 
Remote Sensing Board (BCRS). 



REFERENCES

Joyce, T, C. Corry and M. Stalcup (1991) WHPO Publication 90-1 Revision 1 
    Requirements for WOCE Hydrographic Programme Data Reporting WOCE Report 
    67/91 Unpublished Manuscript

van Aken, H. (1990) Dutch-Warp 1990 R/V TYRO Cruise Report Part 1: WOCE Section 
    AR7E


Data processing notes


Date      Contact         Data Type     Data Status  Summary  
------------------------------------------------------------------------
04/07/98  Schott          Cruise ID     Data Update  North Atlantic cruise list  
          
01/20/00  Huynh           DOC           Website Updated  pdf, txt versions online  
          
11/21/00  Uribe           DOC           Submitted  See Note:  2000.11.21  KJU
          File contained here is CRUISE SUMMARIES and NOT sumfiles.  Files 
          listed below should be considered WHP DOC files. Documentation is 
          online.

          2000.10.11 KJU
          Files were found in incoming directory under whp_reports. This 
          directory was zipped, files were separated and placed under proper 
          cruise. All of them are sumfiles.
          Received 1997 August 15th.
          
03/23/01  Uribe           CTD/BTL/SUM    Website Updated  Expocodes Updated  
          Expocodes for bottle and sum were modified.  Expocodes in all ctd 
          files have been edited to match the underscored expocode in the sum 
          and bottle files. New files were zipped and replaced existing ctd 
          files online. Old files were moved to original directory. 
          
12/14/01  Uribe           CTD           Website Updated  CSV File Added  CTD 
          has been converted to exchange using the new code and put online.
          
01/31/02  Uribe           BTL           Website Updated  CSV File Added  Bottle 
          has been converted to exchange and put online. Data was checked with 
          JOA.
          
05/01/02  Bartolacci      CTD, BOT, SUM  Data update  All files need format 
          checking.   
          
07/22/02  Buck            CTD           Website Updated  Expocodes edited to 
          reflect HYD and SUM  Edited expocodes in the CTD file to reflect 
          proper expocodes in both HYD and SUM files.


