Physical oceanographic investigations in the Weddell Sea
40°W
30°W
20°W
bow
IO°E
20°E
30°E
0 Potential temperature at the temperature maximum core layer within the Weddell deep water in 1976— 77 and 1977— 78 austral summers. A temperature maximum below 0°C Is highly inconsistent with historical data for the open ocean of the Weddell.
References
Carmack, E. C., and Foster, T. D. 1975. On the flow of water out of the Weddell Sea. Deep-Sea Research, 22, 711-724. Foster, T. D., and Carmack E. C. 1976. Frontal zone mixing and antarctic bottom water formation in the southern Weddell Sea. DeepSea Research, 23, 301-317.
Physical oceanographic investigations in the Weddell Sea THEODORE D. FOSTER Center for Coastal Marine Studies University of California Santa Cruz, California 95064 ARNE FOLDVIK Geofysisk Inst it utt Universitetet i Bergen Bergen, Norway N-5014 JASON H. MIDDLETON School of Physics University of New South Wales Kensington, New South Wales, Australia 2033 The last phase of the International Weddell Sea Oceanographic Expedition has involved four cruises to the Weddell Sea: Polarsirkel in 1977 and 1979, Glacier in 1978, and Polar Sea in 1980. We now have data from nine current meters with records up to 630 days long and more than 300 vertical profiles 100
Gordon, A. L. 1978. Deep antarctic convection west of Maud Rise. Journal of Physical Oceanography, 8(4), 600-612. Gordon, A. L. 1981. Seasonality of southern ocean sea ice. Journal of Geophysical Research, 86(C5), 4193-4197. Killworth, P. D. 1979. On "chimney" formations in the ocean. Journal of Physical Oceanography, 9, 531-554. Martinson, D. C., Killworth, P. D., and Gordon, A. L. 1981. A convective model for the Weddell polynya. Journal of Physical Oceanography, 11(4), 466-488.
of temperature, salinity, and oxygen. These observations were concentrated in a relatively small area at the shelf break of the southern Weddell Sea near 74°S 40°W in order to study the mixing processes that lead to the formation of bottom water. Although the data are still being evaluated, several interesting features are evident. The power spectra of the current meter data show that energy levels of velocity fluctuations at periods longer than about 2 days are much higher on the continental slope than on the shelf proper. The energy levels of velocity fluctuations at tidal periods, however, are lower on the slope than on the shelf. The total energy of velocity fluctuations is dominated by tidal effects and thus is stronger on the shelf than on the slope. The longer period velocity fluctuations seem to be consistent with a shelf wave origin. Power spectra of temperature fluctuations indicate that highest levels are right at the shelf break. This agrees with the higher levels of temperature fine structure found at the shelf break from the vertical profiles. A fairly consistent picture of the mixing processes that occur near the shelf break in the southern Weddell Sea thus is beginning to emerge from the data obtained during the 1977 to 1980 cruises. This work was supported in part by National Science Foundation grants OFF 78-07797 and OFF 79-20384. ANTARCTIC JOURNAL
30°W
20°W
bow
IO°E
20°E
30°E
0 Potential temperature at the temperature maximum core layer within the Weddell deep water in 1976— 77 and 1977— 78 austral summers. A temperature maximum below 0°C Is highly inconsistent with historical data for the open ocean of the Weddell.
References
Carmack, E. C., and Foster, T. D. 1975. On the flow of water out of the Weddell Sea. Deep-Sea Research, 22, 711-724. Foster, T. D., and Carmack E. C. 1976. Frontal zone mixing and antarctic bottom water formation in the southern Weddell Sea. DeepSea Research, 23, 301-317.
Physical oceanographic investigations in the Weddell Sea THEODORE D. FOSTER Center for Coastal Marine Studies University of California Santa Cruz, California 95064 ARNE FOLDVIK Geofysisk Inst it utt Universitetet i Bergen Bergen, Norway N-5014 JASON H. MIDDLETON School of Physics University of New South Wales Kensington, New South Wales, Australia 2033 The last phase of the International Weddell Sea Oceanographic Expedition has involved four cruises to the Weddell Sea: Polarsirkel in 1977 and 1979, Glacier in 1978, and Polar Sea in 1980. We now have data from nine current meters with records up to 630 days long and more than 300 vertical profiles 100
Gordon, A. L. 1978. Deep antarctic convection west of Maud Rise. Journal of Physical Oceanography, 8(4), 600-612. Gordon, A. L. 1981. Seasonality of southern ocean sea ice. Journal of Geophysical Research, 86(C5), 4193-4197. Killworth, P. D. 1979. On "chimney" formations in the ocean. Journal of Physical Oceanography, 9, 531-554. Martinson, D. C., Killworth, P. D., and Gordon, A. L. 1981. A convective model for the Weddell polynya. Journal of Physical Oceanography, 11(4), 466-488.
of temperature, salinity, and oxygen. These observations were concentrated in a relatively small area at the shelf break of the southern Weddell Sea near 74°S 40°W in order to study the mixing processes that lead to the formation of bottom water. Although the data are still being evaluated, several interesting features are evident. The power spectra of the current meter data show that energy levels of velocity fluctuations at periods longer than about 2 days are much higher on the continental slope than on the shelf proper. The energy levels of velocity fluctuations at tidal periods, however, are lower on the slope than on the shelf. The total energy of velocity fluctuations is dominated by tidal effects and thus is stronger on the shelf than on the slope. The longer period velocity fluctuations seem to be consistent with a shelf wave origin. Power spectra of temperature fluctuations indicate that highest levels are right at the shelf break. This agrees with the higher levels of temperature fine structure found at the shelf break from the vertical profiles. A fairly consistent picture of the mixing processes that occur near the shelf break in the southern Weddell Sea thus is beginning to emerge from the data obtained during the 1977 to 1980 cruises. This work was supported in part by National Science Foundation grants OFF 78-07797 and OFF 79-20384. ANTARCTIC JOURNAL
