Heat, Salt, and Momentum Fluxes Through the Pycnocline in the Eastern Weddell Sea: Renewal

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9615524 Padman The proposed work is an extension of the data set obtained as part of an integrated research program ("Anzflux") into the oceanographic structure of upper mixed layer of the eastern Weddell Sea. It was carried out from the RVIB Nathaniel B. Palmer in the austral winter of 1994. This component of the integrated program was an effort to measure high frequency vertical profiles of velocity and temperature using a Rapid Sampling Vertical Profiler, a tethered sensor system developed by the principal investigator that free falls through the upper 250 meters of the ocean. The overall objective of this project is to study the dynamics of momentum and energy fluxes in the upper mixed layer, and to investigate the processes that determine the stability of the pycnocline. Particular emphasis is placed on the response of the pycnocline to the mesoscale velocity field, internal waves, and other coherent turbulence features. The specific goal of this extension is to model the fluxes of heat and buoyancy associated with double-diffusive convection, and the impact of tidal currents on mixing in the upper layers of the Weddell Sea. These measurements, in conjunction with other concurrent experiments to quantify the energy brought to the underside of the ice, will form the basis of a regional study of the processes responsible for the relatively thick upper mixed layer and thin ice cover. It is believed that these conditions are only marginally stable, and are maintained by a relatively high upward heat flux, which, if interrupted, could lead to deep vertical convection, and a significant change in the oceanic climate. ***