An assessment of geosynchronous satellite soundings retrieved with the aid of asynoptic radiosonde profiles

Abstract

Geosynchronous satellite soundings from the VISSR Atmospheric Sounder (VAS) have difficulty resolving thermal variations in the troposphere associated with mesoscale dynamical processes. For example, VAS soundings retrieved during a late winter storm on 6 March 1982 scarcely resolved a mid-tropospheric cold pool and a low-level inversion which were captured by a special radiosonde network established as part of an Atmospheric Variability Experiment (AVE) in the south-central United States. In this paper, VAS radiances from the 6 March 1982 AVE/VAS case are re-processed using supplementary radiosonde soundings obtained at NWS radiosonde sites in the central United States to construct a local regression retrieval matrix. The re-processed VAS retrievals are compared to the original VAS retrievals and to an independent mesoscale radiosonde network located in north-central Texas. The re-processed VAS retrievals delineate the three-dimensional mesoscale temperature fields for this case with significantly improved accuracy, indicating that the poor resolution from the previous retrievals was not due to unexpected limitations in the satellite radiometer. More importantly, in order to obtain accurate upper-air temperature analyses over the United States at mesoscale resolution, the results from this case suggest that it may be necessary to develop a system which combines temperature and moisture profiles observed at selected sites in an asynoptic ground-based network (using either balloons or upward-looking microwave sensors) with infrared radiances observed at 30 km horizontal resolution from the geosynchronous sounder, using the VAS satellite data to fill in the gaps between the ground-based measurements.