Tropical synoptic composites in VAS, OLR and TOVS radiance data

The horizontal structure of specific tropical synoptic features are compared with the features of a zonal mean ITCZ using four different forms of satellite radiance data: daily gridded OLR data, GOES VAS water vapor imagery, brightness temperatures from TOVS water vapor channels (6.7 and 7.3 microns), and brightness temperature vectors for a complete set of TOVS channels. All of the data are composited over many events to minimize the effects of missing data, sampling errors, and system variability. The major differences between the observing systems are examined, focusing on resolution and clouds. It is found that the ITCZ exhibits a zonally symmetric convective phase and an enhanced regional convective phase (plumes), both of which can be differentiated from climatological mean behavior.