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- Title
Uncertainties of GPM DPR Rain Estimates Caused by DSD Parameterizations.
- Authors
Liao, Liang; Meneghini, Robert; Tokay, Ali
- Abstract
A framework based on measured raindrop size distribution (DSD) data has been developed to assess uncertainties in DSD models employed in Ku- and Ka-band dual-wavelength radar retrievals. In this study, the rain rates and attenuation coefficients from DSD parameters derived by dual-wavelength algorithms are compared with those directly obtained from measured DSD spectra. The impact of the DSD gamma parameterizations on rain estimation from the Global Precipitation Measurement mission (GPM) Dual-Frequency Precipitation Radar (DPR) is examined for the cases of a fixed shape factor μ as well as for a constrained μ-that is, a μ-Λ relation (a relationship between the shape parameter and slope parameter Λ of the gamma DSD)-by using 11 Particle Size and Velocity (Parsivel) disdrometer measurements with a total number of about 50 000 one-minute spectra that were collected during the Iowa Flood Studies (IFloodS) experiment. It is found that the DPR-like dual-wavelength techniques provide fairly accurate estimates of rain rate and attenuation if a fixed- μ gamma DSD model is used, with the value of μ ranging from 3 to 6. Comparison of the results reveals that the retrieval errors from the μ-Λ relations are generally small, with biases of less than ±10%, and are comparable to the results from a fixed- μ gamma model with μ equal to 3 and 6. The DSD evaluation procedure is also applied to retrievals in which a lognormal DSD model is used.
- Subjects
RAINDROP size; GLOBAL Precipitation Climatology Project; METEOROLOGICAL precipitation; RADAR; PARTICLE size determination; VELOCITY
- Publication
Journal of Applied Meteorology & Climatology, 2014, Vol 53, Issue 11, p2524
- ISSN
1558-8424
- Publication type
Article
- DOI
10.1175/JAMC-D-14-0003.1