The Statistical Analysis and Display Program for GPM Validation Network Geometry-Matched PR and GV Data Sets

Goddard Space Flight Center
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The IDL procedure provides the capability to compute statistics and generate displays of PR and GV reflectivity from geometry-matched data produced by the GPM Validation Network prototype. These data are contained in a set of netCDF data files, one per “rainy” site overpass: a TRMM PR overpass of a ground radar (GV) site, with precipitation echoes present, referred to below as an “event”. The procedure computes and displays tables of mean differences (PR-GV) between the PR and GV reflectivity from the geo-matched data for a selected event, with the data stratified into vertical layers in two manners: (1) by height above the surface, in 1.5-km-deep layers, for 15 levels centered from 1.5 to 19.5 km, and (2) into three layers defined by proximity to the bright band (freezing level): above, within, and below the bright band. For purposes of the latter, match-up samples are categorized as above (below) the bright band if their base (top) is 500 m or more above (750 m or more below) the mean bright band height. The remaining points are assigned as within the bright band. The mean bright band height is computed from the bright band analysis in the TRMM PR 2A-25 product. Only the attenuation-corrected PR reflectivity is used in the program, even though the “raw” PR reflectivity also is present in the netCDF data files.

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