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[IDV #OHK-595448]: question about WSR-88D Level-II data

Hi Michael-

It will depend on the software being used to display the data.  The IDV does 
take into account the curvature of the earth for the 2 and 3D displays.  Other 
software may not.

Don Murray

> I don't know if UNIDATA is the right place for this question...but
> perhaps if it can't be answered through you guys, maybe you could point
> me in the right direction.
> 
> I am trying to get some info of the mapping (ground projection) of
> WSR-88D data using whatever software.  I am going to assume that the
> same coordinate calculation process is done regardless of moment and
> scan angle...and this focuses on the universally distributed "NEXRAD"
> data that can be read by numerous pieces of "meteorological" software
> (i.e. through the NCDC)....although I admit I don't know too much
> about the nuts and bolts of the distributed data.  I am neglecting the
> increasing bin size with distance for this discussion...
> 
> I essentially want to verify that the coordinates (lat/lon) of every 2-D
> bin/polygon have been calculated with consideration of the curvature of
> the earth.  Really not an issue unless a good distance from the radar
> site and at a high altitude.  But I want to make sure that when looking
> at target data that has been retrieved at 300km from the radar site at a
> height of 11km (for example)...that the NEXRAD data is distributed in such
> a way that when it is mapped using my favorite software, the polygons
> correspond to the lat/lon underneath the target (which considers the
> earth surface)...and places it a bit further from the radar site than
> if the earth was flat (also stretching it out a bit).
> 
> A really silly way I visualize this to help me is that if there was a
> 20km tall building normal to the earth surface at a distance of 300km
> from the rad ar site...as each scan angle of the radar increased, the
> radar-detected range (slant range) of the building would increase.
> However when all of buildin g retrievals (and their unique lat/lon
> boundaries) from different scans were plotted on a map (common weather
> radar projection) they would all be locate d at the same place on the
> map, which would exactly correspond to the base of the bulding.....and
> not represent the difference in slant range.
> 
> I assume this to be the case since height estimations are done with
> regard to the earth curvature (and refraction coefficient) but I guess
> I need to make sure that this is the standard for NEXRAD data and no
> geographical correct ion needs to be made to the coordinates in the data.
> 
> Thanks,
> Mike
> 
> 
> 
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Ticket Details
===================
Ticket ID: OHK-595448
Department: Support IDV
Priority: Normal
Status: Open