[show abstract][hide abstract] ABSTRACT: A hydrometeor classification system based on a fuzzy logic technique using dual-polarization radar measurements of precipitation is presented. In this study, five dual-polarization radar measurements (namely horizontal reflectivity, differential reflectivity, specific differential phase, correlation coefficient, and linear depolarization ratio) and altitude relating to environmental melting layer are used as input variables of the system. The hydrometeor classification system chooses one of nine different hydrometeor categories as output. The system presented in this paper is a further development of an existing hydrometeor classification system model developed at Colorado State University (CSU). The hydrometeor classification system is evaluated by comparing inferred results from the CSU CHILL Facility dual-polarization radar measurements with the in situ sample data collected by the T-28 aircraft during the Severe Thunderstorm Electrification and Precipitation Study.
IEEE Transactions on Geoscience and Remote Sensing 05/2005; · 3.47 Impact Factor
[show abstract][hide abstract] ABSTRACT: Monitoring of precipitation using high frequency radar systems such as X-band is becoming increasingly popular due to their lower cost compared to their counterpart at S-band. Meteorological radar systems operating at S-band frequencies are not affected by attenuation due to precipitation. The S-band radar systems are typically expensive with large antennas, and high power transmitters. Recently, network of meteorological radar systems at higher frequencies such as X band are being pursued, especially for low cost and targeted applications, such as coverage over a city or a small basin. Attenuation correction of the signal returns from these radars is important for quantitative applications. In order to design the radar systems as well as evaluate algorithm development, it is useful to have simultaneous X-band observation with and without the impact of path attenuation. The only way to collect such data is from dual frequency radar system with matched beams. This paper presents a methodology to generate realistic range profiles of radar observations at attenuating frequencies, such as X band, for rain medium. Fundamental microphysical properties of precipitation, namely size and shape distribution information are used to generate realistic profiles of X-band starting with S-band observation. Conditioning the simulation from S-band maintains the natural distribution of rainfall microphysical parameters. Data form the Colorado State University CHILL radar and the National Center for Atmospheric Research S-POL radar are used to simulate X-band radar observations. The two procedures and sample applications are presented.
[show abstract][hide abstract] ABSTRACT: This paper describes a methodology for reflectivity and attenuation retrieval in a networked radar environment. Electromagnetic waves backscattered from a common volume are attenuated differently along the different paths. Solution of the specific attenuation distribution is proposed by solving the integral equation for reflectivity, in a manner similar to that used with a differential phase constraint. The set of governing integral equations describing the backscatter and propagation of common resolution volume are solved simultaneously with constraints on observed total path attenuation. The algorithms developed are evaluated on simulated X-band radar observations in rain obtained from S-band measurements by CSU-CHILL radar. Retrieved reflectivity and specific attenuation using the iterative method show good agreement with intrinsic reflectivity and specific attenuation
[show abstract][hide abstract] ABSTRACT: Following the success of the Tropical Rainfall Measuring Mission (TRMM), considerable effort has been directed at the next generation of space-based precipitation radar (PR) to be launched aboard the Global Precipitation Measuring (GPM) core satellite. The GPM mission concept is centered on the deployment of a core observatory satellite with an active dual-frequency precipitation radar (DPR), operating at Ku and Ka bands. The DPR aboard the GPM core satellite is expected to improve our knowledge of precipitation processes relative to the single-frequency on microphysics, and better accuracies in rainfall and liquid water content retrievals. This paper presents a new algorithm to retrieve parameters of drop size distribution of GPM- DPR. Models have been built for GPM-DPR classification based on intensive study of APR2 (second generation airborne precipitation radar) data from NAMMA (NASA African Monsoon Multidisciplinary Analysis) experiment.