Atmospheric Wind retrievals from Satellite soundings over the Polar Plateau regions

Detailed knowledge of the atmospheric motion over Antarctica is very important for understanding the Antarctic climate variability. Due to the sparseness of the radiosonde stations, current knowledge of the atmospheric wind structure over Antarctica depends crucially on the analysis/reanalysis systems. These model-based analyses have added to our understanding by helping to explain observed data. However, the models are ultimately only as good as the data available to them. Large errors have been found when these analysis/reanalysis winds are validated against independent radiosonde observations and satellite-derived cloud-drift and moisture winds.

This study attempts to derive the Antarctic atmospheric wind structure from satellite observations. Temperature soundings from the Television Infrared Observational Satellite (TIROS) Operational Vertical Sounder (TOVS) Pathfinder A dataset and a Special Sensor Microwave Imager (SSM/I) satellite-based surface wind field are used to derive the wind fields. The wind retrieval method used here is based on that developed by Zou and Van Woert (2002) in which the thermal wind derived from the satellite temperature soundings is added to the surface wind subject to the mass conservation constraint. In addition, a more generalized surface boundary condition is included in the retrieval algorithm so that it can retrieve the atmospheric wind over the plateau area such as the Antarctic continent. Results suggest that the satellite winds developed here exhibit some features similar to the satellite moisture winds when they are compared with each other at the assigned moisture wind level. However, the satellite-derived atmospheric wind structure shows significant differences from the NCEP/NCAR Rreanalysis-2 as well as other reanalysis winds over the Antarctic coast. The reasons for these differences will be discussed.