the Expedition ARKTIS-XIX/4 of the research vessel POLARSTERN ...

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Altimeters Model 2110-2, SN 189 and SN 208 and Wetlabs C-Star
Transmissiometers SN 403 and SN 267 were mounted on the carousels. During the
cruise a total number of 184 water samples were analysed with a Guildline Autosal
8400B salinometer, and IAPSO standard seawater batch number P141, K=0.99993.
20 salinity samples were brought back to AWI for analysis there. The CTD sensors
were calibrated before and after the cruise by Sea-Bird Electronics. 138 water
samples were taken at 10 stations from 7 levels (10, 30, 50, 70, 100, 150 and 200 m)
to measure the concentration of the oxygen isotope � 18 O.
Underway measurements with a ship-borne narrow band 150 kHz ADCP from RD
Instruments and a Sea-Bird SBE45 thermo-salinograph measurements were
conducted along the transect to supply temperature, salinity and current data at a
much higher spatial resolution than given through the moorings. Two thermosalinographs
were in use, one in 6 m depth in the bow thrusters tunnel and one in 11
m depth in the keel. Both instruments are controlled by taking water samples which
are measured on board.
Preliminary Results
The data from the moored instruments were read out from the memories but need to
be carefully processed in Bremerhaven. Therefore no results can be given here.
The evaluation of the hydrographic data occurred on the basis of preliminary data
available on board. The post-cruise calibration might result in minor changes.
The temperature and salinity sections across the Fram Strait are shown in Fig. 7-4.
The main core of northward flowing warm and saline Atlantic Water is found at the
eastern side of the transect in the shallow to intermediate layers. The West
Spitsbergen Current is visible at the eastern slope by downward sloping isolines. The
Atlantic Water reaches significantly further to the west than during previous years. On
the western side the cold and low saline Polar Waters of the East Greenland Current
can be seen. However, due to missing time it could not be measured on the shelf. In
the deep layers a slight cooling is to be seen in the east and a decrease of salinity.
To identify the longer term variability, time series of mean temperatures and salinities
for typical water masses were derived for two depth intervals (5 ÷ 30 m and
50 ÷ 500 m) (Fig. 7-5). Three characteristic areas were distinguished in relation to the
main flows: the West Spitsbergen Current (WSC) between the shelf edge and 5°E,
the Return Atlantic Current (RAC) between 3°W and 5°E, and Polar Water in the East
Greenland Current (EGC) between 3°W and the Greenland Shelf. The temperature
of the near surface layer in the West Spitsbergen Current showed a slight decrease
since last year which might be affected by seasonal variability. However, the
temperature stays high in comparison to the late 80ties. The temperature of the water
of the Return Atlantic Current increased further since last year. Mean salinities
observed in the West Spitsbergen Current were close to those measured last year
while those of Return Atlantic Current increased further. The strong decrease of the
mean salinities in the East Greenland Current which was observed in 2002 is fully
compensated indicating rather high interannual variability or aliasing of the seasonal
signal but no clear longer period trend. The mean temperature in the EGC decreased