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Article Type:
Research Article

Estimation of Raindrop Size Distribution Parameters from Polarimetric Radar Measurements

Eugenio GorgucciIstituto di Fisica dell'Atmosfera, Consiglio Nazionale dell Ricerche, Rome, Italy

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V. ChandrasekarColorado State University, Fort Collins, Colorado

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V. N. BringiColorado State University, Fort Collins, Colorado

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Gianfranco ScarchilliIstituto di Fisica dell'Atmosfera, Consiglio Nazionale dell Ricerche, Rome, Italy

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Print Publication:
01 Aug 2002
DOI:
https://doi.org/10.1175/1520-0469(2002)059<2373:EORSDP>2.0.CO;2
Page(s):
2373–2384
Restricted access

Abstract

Estimation of raindrop size distribution over large spatial and temporal scales has been a long-standing goal of polarimetric radar. Algorithms to estimate the parameters of a gamma raindrop size distribution model from polarimetric radar observations of reflectivity, differential reflectivity, and specific differential phase are developed. Differential reflectivity is the most closely related measurement to a parameter of the drop size distribution, namely, the drop median diameter (D0). The estimator for D0 as well as other parameters are evaluated in the presence of radar measurement errors. It is shown that the drop median diameter can be estimated to an accuracy of 10%, whereas the equivalent intercept parameter can be estimated to an accuracy of 6% in the logarithmic scale. The estimators for the raindrop size distribution parameters are also evaluated using disdrometer data based simulations. The disdrometer based evaluations confirm the accuracy of the algorithms developed herein.

Corresponding author address: Dr. Eugenio Gorgucci, Istituto di Fisica dell'Atmosfera, CNR, Area di Ricerca Roma-Tor Vergata, Via del Fosso del Cavaliere, Rome 100-00133, Italy. Email: gorgucci@radar.ifa.rm.cnr.it

Abstract

Estimation of raindrop size distribution over large spatial and temporal scales has been a long-standing goal of polarimetric radar. Algorithms to estimate the parameters of a gamma raindrop size distribution model from polarimetric radar observations of reflectivity, differential reflectivity, and specific differential phase are developed. Differential reflectivity is the most closely related measurement to a parameter of the drop size distribution, namely, the drop median diameter (D0). The estimator for D0 as well as other parameters are evaluated in the presence of radar measurement errors. It is shown that the drop median diameter can be estimated to an accuracy of 10%, whereas the equivalent intercept parameter can be estimated to an accuracy of 6% in the logarithmic scale. The estimators for the raindrop size distribution parameters are also evaluated using disdrometer data based simulations. The disdrometer based evaluations confirm the accuracy of the algorithms developed herein.

Corresponding author address: Dr. Eugenio Gorgucci, Istituto di Fisica dell'Atmosfera, CNR, Area di Ricerca Roma-Tor Vergata, Via del Fosso del Cavaliere, Rome 100-00133, Italy. Email: gorgucci@radar.ifa.rm.cnr.it

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