9315934 Ackley The proposed work is part of an integrated research program ("Anzflux") into the oceanographic structure of upper mixed layer of the eastern Weddell Sea. It is to be carried out from the RVIB Nathaniel B. Palmer in the austral winter of 1994. The work proposed here is a spatially small-scale and mesoscale study of the growth of sea ice in open water, and the physical, chemical, biological, and thermal properties of the existing ice cover. The rates of sea ice growth determine salt and latent heat fluxes that affect the density of the oceanic surface layer. Additionally, longer-term heat and mass balance measurements on various ice types in the vicinity of the ship will be carried out. This involves installing ice thickness gauges, thermistor (temperature) strings, and stress sensors, which will be sampled periodically over the duration of the drift. Radar backscatter and passive microwave emission measurements will be made at several frequencies to establish the dielectric properties of the sea ice and to provide ground truth information for future satellite-based radar experiments. 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. ***
