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Optimal thresholds for the estimation of area rain-rate moments by the threshold methodOptimization of the threshold method, achieved by determination of the threshold that maximizes the correlation between an area-average rain-rate moment and the area coverage of rain rates exceeding the threshold, is demonstrated empirically and theoretically. Empirical results for a sequence of GATE radar snapshots show optimal thresholds of 5 and 27 mm/h for the first and second moments, respectively. Theoretical optimization of the threshold method by the maximum-likelihood approach of Kedem and Pavlopoulos (1991) predicts optimal thresholds near 5 and 26 mm/h for lognormally distributed rain rates with GATE-like parameters. The agreement between theory and observations suggests that the optimal threshold can be understood as arising due to sampling variations, from snapshot to snapshot, of a parent rain-rate distribution. Optimal thresholds for gamma and inverse Gaussian distributions are also derived and compared.
Document ID
19930043208
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Short, David A.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Shimizu, Kunio
(Tokyo Science Univ. Noda, Japan)
Kedem, Benjamin
(Maryland Univ. College Park, United States)
Date Acquired
August 16, 2013
Publication Date
February 1, 1993
Publication Information
Publication: Journal of Applied Meteorology
Volume: 32
Issue: 2
ISSN: 0894-8763
Subject Category
Meteorology And Climatology
Accession Number
93A27205
Distribution Limits
Public
Copyright
Other

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