Weddell Sea Upper Ocean Turbulence Analysis Modeling

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*** 9725478 McPhee This study is concerned with the analysis of an extensive data set obtained by the principal investigator in the context of two interdisciplinary field projects in the Weddell Sea: the Joint U.S.-Russian Ice Camp in 1992 and Anzflux in 1994. The data set consists of direct measurements of Reynolds stresses and turbulent heat fluxes in the uppermost 100 meters of the ocean under a continuous sea ice cover, and was the first such observations made in the Southern Ocean. The objective of the analysis is continued development of a turbulence closure technique in the numerical modelling of the upper ocean, and to describe the structure of boundary layer turbulence under exceptionally wide ranges of surface stress and buoyancy flux. A frequent criticism of current upper ocean models is that their representations of turbulent exchange processes are arbitrarily adjusted to reproduce the few available observed time series of upper ocean structure. This work will provide the basis for a significantly improved modelling of upper ocean turbulence by requiring the model algorithms to reproduce a wide range of turbulence intensities, and will include a novel approach to specifying the eddy properties of the upper ocean. These analyses, in conjunction with concurrent analyses of other experiments carried out in the two field projects, will produce a framework for quantifying the energy brought to the underside of the ice, and 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 the sea ice cover is only marginally stable in the face of the high upward heat flux, and if this were interrupted, could lead to deep vertical convection and a significant change in the ocean climate. ***