SATELLITE-MODEL COUPLED ANALYSIS OF CONVECTIVE POTENTIAL IN FLORIDA WITH VAS WATER-VAPOR AND SURFACE-TEMPERATURE DATA

A system for time-continuous mesoscale weather analysis is applied to a study of convective cloud development in central Florida. The analys is system incorporates water vapor concentrations and surface temperat ures retrieved from infrared VISSR (Visible-Infrared Spin Scan Radiome ter) Atmospheric Sounder (VAS) satellite data, with coupling between t he retrieval process and time integration of a mesoscale model. Analys es prepared with variations of this coupled system are compared with a control numerical analysis prepared with only conventional meteorolog ical observations and are validated against surface and upper-air data collected for the Convection and Precipitation/Electrification experi ment. The coupled analyses assimilate six sets of VAS data over an 8-h period on 19 July 1991 and depict water vapor gradients at far greate r horizontal resolution than is available from conventional observatio ns and with an overall accuracy better than the control analysis. The coupled system's ability to assimilate multiple sets of VAS data, with meteorological continuity provided by the model, was important to the accuracy and the breadth of coverage of the water vapor analysis amid changing cloud cover conditions. The surface temperature information provided by the VAS was neither harmful nor very helpful to the mesosc ale analysis for this case, owing to the combination of mediocre satel lite viewing conditions and the apparent low importance of land surfac e temperature gradients to the meteorology of the day. Convective stab ility parameters computed from the coupled analysis data at 1000 local time corresponded closely with patterns of cloud development in the e arly afternoon.