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Reducing Spaceborne-Doppler-Radar Rainfall-Velocity ErrorA combined frequency-time (CFT) spectral moment estimation technique has been devised for calculating rainfall velocity from measurement data acquired by a nadir-looking spaceborne Doppler weather radar system. Prior spectral moment estimation techniques used for this purpose are based partly on the assumption that the radar resolution volume is uniformly filled with rainfall. The assumption is unrealistic in general but introduces negligible error in application to airborne radar systems. However, for spaceborne systems, the combination of this assumption and inhomogeneities in rainfall [denoted non-uniform beam filling (NUBF)] can result in velocity measurement errors of several meters per second. The present CFT spectral moment estimation technique includes coherent processing of a series of Doppler spectra generated in a standard manner from data over measurement volumes that are partially overlapping in the along-track direction. Performance simulation of this technique using high-resolution data from an airborne rain-mapping radar shows that a spaceborne Ku-band Doppler radar operating at signal-to-noise ratios greater than 10 dB can achieve root-mean-square accuracy between 0.5 and 0.6 m/s in vertical-velocity estimates.
Document ID
Acquisition Source
Jet Propulsion Laboratory
Document Type
Other - NASA Tech Brief
Tanelli, Simone
(California Inst. of Tech. Pasadena, CA, United States)
Im, Eastwood
(California Inst. of Tech. Pasadena, CA, United States)
Durden, Stephen L.
(California Inst. of Tech. Pasadena, CA, United States)
Date Acquired
August 24, 2013
Publication Date
September 1, 2008
Publication Information
Publication: NASA Tech Briefs, September 2008
Subject Category
Communications And Radar
Report/Patent Number
Distribution Limits
Public Use Permitted.
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