Combined Ku and Ka band observations of precipitation and retrievals for GPM Ground validation
ABSTRACT The dual-frequency precipitation radar (DPR) aboard the GPM (Global Precipitation Measurement) core satellite is expected to improve our knowledge of precipitation processes. Ground validation is an integral part of all satellite precipitation missions which helps provide insight into the physical basis of the retrieval algorithm. A dual-frequency (Ku and Ka band) and dual-polarization ground radar will be built in near future to perform cross validation with GPM. This paper presents a new algorithm to retrieve parameters of the drop size distribution from this dual-frequency and dual-polarization ground. The method is based on combination of DFR (dual frequency ratio) and dual-polarization approach. Attenuation correction is solved within the retrieval process. The proposed algorithm is evaluated based on simulated Ku and Ka band realistic observations, for rain, melting layer and ice parts.
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ABSTRACT: Empirical analyses are shown to imply variation in the shape or analytical form of the raindrop size distribution consistent with that observed experimentally and predicted theoretically. These natural variations in distribution shape are demonstrated by deriving relationships between pairs of integral rainfall parameters using a three parameter gamma drop size distribution and comparing the expressions with empirical. There comparisons produce values for the size distribution parameters which display a systematic dependence of one of the parameters on another between different rainfall types as well as from moment to moment within a given rainfall type. The implications of this finding are explored in terms of the use of a three-parameter gamma distribution in dual-measurement techniques to determine rainfall rate.Journal of Climate Applied Meteorology. 01/1983; 22:1764-1775.
- Journal of Atmospheric and Oceanic Technology 01/1990; 7(6):829-840. · 1.69 Impact Factor
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ABSTRACT: A question arising from the recent interest in spaceborne weather radar is what methods can be used to estimate precipitation parameters from space. In this paper, dual-wavelength airborne radar data obtained from flights conducted during 1988 and 1989 are used to compare rain rates derived from backscattering and attenuation methods. To help interpret the results the surface reference methods are studied by means of scatterplots of the surface cross sections at the two frequencies under rain and no-rain conditions. Approximate criteria are given on combining attenuation and backscattering methods to increase the effective dynamic range of the radar. The dual-wavelength capability of the radar is also used to examine the vertical structure of the precipitation. Another factor affecting the accuracy of the methods is the drop-size distribution. In the final section of the paper a procedure to estimate the profiled drop-size distribution is applied to the measured radar data.09/1992;