A. CRUISE NARRATIVE:  ISS02, IR01W, IR03N (western Arabian Sea)

A.1. HIGHLIGHTS

                        WHP CRUISE SUMMARY INFORMATION

               WOCE section designation  ISS02, IR01W, IR03N
      Expedition designation (EXPOCODE)  06MT32_6
            Chief Scientist/affiliation  Friedrich Schott
                                  Dates  1995 AUG 17 - 1995 SEP 19
                                   Ship  R/V Meteor
                          Ports of call  Muscat, Oman to Muscat, Oman
                     Number of stations  CTD: 116     XBT: 114

                                                 23°N 
                  Geographic boundaries  49°E             61°E
                                                 3°S
           Floats and drifters deployed  0
         Moorings deployed or recovered  0
  
                   Contributing Authors  Prof. Friedrich Schott
                                         Monika Rhein 
                                         Olaf Plähn
_______________________________________________________________________________
                            *Prof. Friedrich Schott
   Institut fuer Meereskunde   Duesternbrooker Weg 20   24105 Kiel    Germany
Tel. +49-431-600-4100   Fax. +49-431-600-4102   e-mail: fschott@ifm.uni-kiel.de



B. SCIENTIFIC PROGRAM

The cruise was designated to derive hydrographic data in the Arabian Sea during 
the summer monsoon as part of the WOCE Indian Ocean program.


PARTICIPANTS

Prof. Friedrich Schott            Chief scientist      IfM Kiel
  fschott@ifm.uni-kiel.de
Monika Rhein                      Chlorofluorocarbons  IfM Kiel
  monika.rhein@io-warnemuende.de
Olaf Plähn                        Chlorofluorocarbons  IfM Kiel
  oplaehn@ifm.uni-kiel.de
Martina Elbrächter                CFC-Lab              IfM Kiel
  melbraechter@ifm.uni-kiel.de

IfM Kiel: Institut für Meereskunde, 24105 Kiel, Germany



CHLOROFLUOROCARBONS
(Monika Rhein and Olaf Plähn


SAMPLE COLLECTION AND TECHNIQUE

All samples were collected from 10 L Niskin bottles. The bottles had 
been cleaned prior to the cruise using isopropanol. All 'O' rings, 
valves, and taps were removed, washed in isopropanol and baked in a 
vacuum oven for 24 hours. The rubber bands on all bottles were replaced 
by stainless steel springs. The personnel for all water sampling and 
handling procedures at the bottles wore one-way gloves to protect the 
valves from grease.

About 100 mL of water were taken from the water bottles with a gastight 
glass syringe (Becton and Dickinson). Then 15-25 mL of the samples were 
transfered to a purge and trap unit and analyzed on board following the 
procedures described in Bullister and Weiss [1988]. The CFCs were 
separated on a packed stainless steel column filled with Porasil C and 
detected with an Electron Capture Detector (ECD). The carrier gas was 
ECD pure Nitrogen, which was additionally cleaned by molsieves (13X mesh 
80/100). The calibration was done using a standard gas with near air 
concentrations to convert the ECD signal in concentrations. The CFC 
values are reported in pmol kg-1 on the SIO93 scale (R. Weiss, SIO).


Figure 1: Accuracy of CFC-11 (*) and CFC-12 (o); replicate samples 
          plotted vs profile number.


PERFORMANCE

During the cruise M32/6 the Kiel CFC system worked continuously. Both 
freon components CFC-11 and CFC-12 had been sampled on 70 CTD Stations 
and 960 water were analyzed successful. The accuracy was checked by 
measuring about 190 water samples twice or more (Figure 1). It was found 
to be for CFC-12 1.1% or 0.0055 pmol kg-1 and 1.2% or 0.006 pmol kg-1 for 
CFC-11.

The mean blank of the sample transfer and the measurement procedure was 
determined by degasing 1 - 2 mL of CFC free deep water. During the 
cruise it was in the order of 0.003 pmol kg-1 for CFC-12 and 0.006 pmol 
kg-1 for CFC-11. Furthermore, CFC free water was created by degasing 5 L 
of seawater with ECD-pure nitrogen gas, to determine blanks of the 
measurement system and the syringes. Analysis of 25 mL of blankwater 
resulted in concentrations of 0.006 pmol kg-1 for both components.

The effciency of the ECD was stable in time for both components (Figure 
2). The temporal variations were only 15%. While CFC-12 showed a 
decrease of the effciency during the cruise to about 85%, the CFC-11 
component did not show a signficant trend, but varied between 95% to 
115%. To correct the temporal drift of the ECD, a calibration curve 
with seven different gas volumes was taken before and after each 
station. The temporal change between two calibration curves was assumed 
to be linear in time. CFC concentrations were calculated by using the 
two neighboured points, supposing that the calibration curve is linear 
between these points.


Figure 2: Temporal evolution of the ECD-effciency during the cruise for 
          the 0.5 mL volume (small) and the 2 mL volume (large).


CONTAMINATION

During the cruise CFC-11 and CFC-12 could not be analyzed for the first 
42 stations (No. 463-504), because of a combination of leakage in the 
ship's air-conditioning system and a small leakage between the stripper 
and a valve in the freon purge and trap unit. On some stations, the CFC-
12 peak was disturbed by the high N2O levels of the samples, these data 
were removed. Comments The CFC concentrations decreased exponentially 
from the surface to about 1000 m depth (Figure 3). At larger depths, CFC 
concentrations were below detection limit. At the surface the mean 
saturation was 103% for CFC-11 and 97% for CFC-12 (Figure 4) [Rhein et 
al., 1997]. As observed during the cruise Meteor 32/4 in June/July 1995, 
the CFC-11 saturation was about 5-6% higher than the values of CFC-12. 
At 400 m depth this difference could not be observed, the saturation of 
both components were equal (15.9%). Low surface-saturation were observed 
at the northern edge of the 'Southern Gyre' (Stat. 521) and at the 
northern edge of the 'Great Whirl' (Stat.545). Due to the decreasing 
wind at the end of the cruise, the upwelling at the coast of Oman 
stopped and the freon concentration were nearly in equilibrium to the 
atmosphere [Plähn, 1999].

The maximum of the mean CFC-11/CFC-12 ratio (Figure 5) is at about 150 m 
depth (SIGMA theta ~ 26) ~ 1.95, downward this ratio decreases (<1.8 at 
800 m, SIGMA theta = 27). The accuracy of the ratio is less than 0.1 if 
the CFC-11 concentration it larger than 0.15 pmol kg-1. The 
concentrations at 700 m depth are less than 10% of the surface-values, 
within this depth-range the error of the ratio increases rapidly.


Figure 3: All CFC-11 concentrations measured during the cruise M32/6 
          versus depth.

Figure 4: CFC-11 (green) and CFC-12 (red) saturation at the surface

Figure 5: CFC-11/CFC-12 ratio versus density



REFERENCES

Bullister, J.L. and R.F. Weiss (1988). Determination of CCl3 F and CCl2 
    F2 in seawater and air. Deep-Sea Res., 35, S. 839-853.

Plähn, O. (1999). Ventilation und Zirkulation in der Arabischen See: 
    Ergebnisse aus Beobachtungen und Modellanalysen. Dissertation, 
    Universität Kiel.

Rhein, M., O. Plähn, and L. Stramma (1997). Tracer distribution in the 
    Arabian Sea, 1995. WOCE Newsletter, 27, S. 12-14.


 
APPENDIX

o  Leg 6 is part of the 1995 Kiel CFC data set including the M32 legs 1 
   and 4 in the Arabian Sea.

o  The station file 'meteor326.sum' includes:
   1 station number
   2 year
   3 month
   4 day
   5 hour: minutes in decimal system
   6 latitude: minutes in decimals
   7 longitude: minutes in decimals
   8 water depth (m)
   9 depth of CTD profile (m)

o  The bottle file 'meteor326.sea' includes:
   1 station number
   2 bottle number
   3 depth (dbar)
   4 in-situ temperature (-C)
   5 salinity (psu)
   6 CFC-12 (pmol kg-1)
   7 CFC-11 (pmol kg-1)
   8 WOCE quality ag for CFC-12 and CFC-11


TECHNICAL INFORMATION

Gas                                 chromatograph Shimadzu GC 14
GC column                           stainless steel, packed with Porasil C
Cooling trap                        with Porapak T and Porasil C
Trap temperatures                  -30-CC, 100-C
Column temperature                  70-CC, isothermal
ECD temperature                     300-C
Electron capture detector           Shimadzu
Software for chromatogram analysis  Shimadzu CLASS C-R4A
Standard gas                        ALM 83959, R. Weiss, SIO

Accuracy                            CFC-11: 1.2% , CFC-12: 1.1%
Blanks                              CFC-11: 0.006 pmol kg-1, 
                                    CFC-12: 0.003 pmol kg-1



WHPO DATA PROCESSING NOTES

Date      Contact     Data Type  Data Status Summary
--------  ----------  ---------  ------------------------------------------------
05/08/00  Rhein       CFCs       Data are Public
          the CFC data
            06MT32_1
            06MT32_6
          can be made public and included in the CD_ROM

03/20/03  Stramma     CTD/BTL    Website Updated;Data are public
          I saw that there are three references with CTD and bottle data listed 
          as non-public.
            These are:
            IR01W 06MT32_1
            IR03N 06MT32_1
            IR03N 06MT32_6
          We like to ask you to make these data public.

03/27/03  Bartolacci  CTD/BTL    Website Updated; Data are public
          I have unencrypted both bottle and CTD files for this cruise. 
          The bottle file contains incorrect number of quality bytes for the 
          number of asterisked columns in the file. Dr.s Schott and Strama have 
          been emailed for course of action with this file. The file is linked, 
          however the data history should reflect the incorrect QUALT1 word. No 
          further action was taken at this time.

          CTD files have been edited so all casts for all station files are 1 
          instead of the previous increasing cast numbering. No stations 
          contained more than one cast as per sumfile. Exchange, netCDF and 
          inventory files were generated for CTD files and linked online. All 
          files are public.

04/02/03  Bartolacci  BTL        Website Updated; BTL file edited/replaced
          A new updated bottle file was received from Dr.Stramma to replace 
          previous bottle file (which contained too many asterisked columns for 
          number of quality bytes).

          New file had columns realigned, name/date stamp added. Format checked 
          new file with no errors after editing. Created exchange netCDF and 
          inventory files.

          Updated web pages and responded to Dr. Sramma's submission email.
          All data for this cruise are now public.

07/02/03  Kappa       DOC        PDF and Text versions of cruise report assembled
          Both PDF and Text docs contain:
            Cruise summary information
            CFC Report
            These WHPO Data Processing Notes
          PDF report also contains:
            Figures for CFC report
            Cruise Track
            Links to Figures from text references
          

