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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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Ben- Ben Kamen wrote:
Anyone? Little help?
Sorry, I thought you had it down.
Ben Kamen wrote:ok - so then let me know if this is possible: I assume we are agreed on what a "gate" is....
In my world a gate is the where the radar value at a particular range, azimuth and elevation angle (tilt) is taken.
Set up two arrays of two dimensions each (az, ra). Range wants to be even km for REF, of course. Az can be any resolution. Even degrees (0-359) is convenient and is assumed below. The two arrays hold the data for averaging one elevation for >1 scan (so two dimensions are enough, but that is a detail). SumZ Holds the sum of Z (not dBZ) for all gates and portions of gatesthat fall in that azimuth and range.
what is Z? N Holds the number of gates that
have contributed to SumZ. This is not usually an integer.
This will be tricky to calculate.
Most Nexrad gates will have azimuths that are not even integers. (An azimuth such as 15.000 degrees is an edge case in the coding.) The procedure is to convert each range gate's dBZ value to Z and compute what two SumZ azimuths it overlaps. Then run along the ranges. Add z*p and z*(1-p) to the two elements of SumZ. Add p and (1-p) to the two elements of N. After all the desired scans have been summed in this way, divide SumZ by N to get average Z and convert to dBZ for displaying. Can that be done in IDV?
It would take some non-trivial Jython or a Java program to do all what you've asked, but conceivably, yes. You'd have to deconstruct each of the sweeps (elevation scan) to get the range and azimuth values and do your comparison/summing. Good luck! Don ************************************************************* Don Murray UCAR Unidata Program dmurray@xxxxxxxxxxxxxxxx P.O. Box 3000 (303) 497-8628 Boulder, CO 80307 http://www.unidata.ucar.edu/staff/donm *************************************************************
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