README file for GPM GV software for comparison of radar rain rate between 
TRMM PR and ground radars, using gridded data contained in netCDF grid files.  

; Copyright © 2008, United States Government as represented by the
; Administrator for The National Aeronautics and Space Administration.
; All Rights Reserved.
;
; EMAIL QUESTIONS OR COMMENTS TO:
;       <Bob Morris> kenneth.r.morris@nasa.gov
;       <Matt Schwaller> mathew.r.schwaller@nasa.gov
;

Within the VN framework, a script (e.g., doSiteSpecificComparisons.sh) queries 
the gpmgv database to assemble a control file, and invokes IDL and the IDL 
batch file doSiteSpecificRainComparisons.bat to compile and run the main 
procedure, doSiteSpecificRainComparisons.pro.  The calling script provides the 
control file pathname to doSiteSpecificRainComparisons.pro via the environment 
variable SSCFILES.  The PR netCDF data is compared to the 2A-53 derived GV netCDF data only.

The top level IDL procedure, doSiteSpecificRainComparisons.pro, opens, reads, and parses the control file to determine the set of site overpass events (as 
determined by the listed PR and GV netCDF file pairs to process) for which to 
compute reflectivity comparison statistics for a site, and calls the procedure 
comparison_pr_gv_rain.pro with the list of files to process for the site.  This 
repeats for each site listed in the control file.   comparison_pr_gv_rain.pro
reads the rain rate and other grid fields from the PR and GV netCDF files, 
computes rain rate difference statistics for the site, and produces a series 
of graphs and tabular summaries of the site-specific statistics.  The procedure 
commonArea_rain.pro is called to stratify the data by: (1) rain type, and (2) 
underlying surface type. The procedure statistics_rain_table.pro produces tabular summaries of rain rate statistics, which it writes to a text file.  The 
same is true for standardError_rain_table.pro, except standard error is 
tabulated.  The procedure bias_rain_table.pro produces tables of PR-GV rain 
rate bias stratified by rain type and by underlying surface type.  Histograms 
of PR and GV rain rate, and scatter plots of PR vs. GV rain rate, also 
stratified by rain type and by underlying surface type, are produced by 
plot_histogram_rain.pro and plot_scaPoint_rain.pro, respectively, which output 
the graphics to Postscript files.


Files:
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doSiteSpecificRainComparisons.bat
doSiteSpecificRainComparisons.pro
comparison_pr_gv_rain.pro
commonArea_rain.pro
statistics_rain_table.pro
standardError_rain_table.pro
bias_rain_table.pro
plot_histogram_rain.pro
plot_scaPoint_rain.pro
README.comparerain.txt (this file)
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Bob Morris, GPM GV (SAIC)
kenneth.r.morris@nasa.gov
August, 2008