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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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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 > > > > ***CONFIDENTIALITY NOTICE***: THIS E-MAIL TRANSMISSION MAY CONTAIN > INFORMATION THAT IS PRIVILEGED, CONFIDENTIAL, PROPRIETARY, SUBJECT TO > COPYRIGHT, AND/OR EXEMPT FROM DISCLOSURE UNDER APPLICABLE LAW. IT IS FOR THE > USE OF INTENDED RECIPIENTS ONLY. If you are not an intended recipient of > this message, please notify the original sender immediately by forwarding > what you received and then delete all copies of the correspondence and > attachments from your computer system. Any use, distribution, or disclosure > of this message by unintended recipients is not authorized and may be > unlawful. > > Ticket Details =================== Ticket ID: OHK-595448 Department: Support IDV Priority: Normal Status: Open