Showing papers by "Robert Meneghini published in 2011"
TL;DR: In this paper, radar signatures are simulated in snow and rain to explore the relation between the differential frequency ratio (DFR), defined as the difference of radar reflectivity factors between Ku- and Ka-bands, and the radar reflectivities factor at Ku-band, ZKu, for different hydrometeor types.
Abstract: An important objective for the Dual-wavelength Ku-/Ka-band Precipitation Radar (DPR) that will be on board the Global Precipitation Measuring (GPM) core satellite, is to identify the phase state of hydrometeors along the range direction. To assess this, radar signatures are simulated in snow and rain to explore the relation between the differential frequency ratio (DFR), defined as the difference of radar reflectivity factors between Ku- and Ka-bands, and the radar reflectivity factor at Ku-band, ZKu, for different hydrometeor types. Model simulations indicate that there is clear separation between snow and rain in the ZKu-DFR plane assuming that the snow follows the Gunn-Marshall size distribution (1958) and rain follows the Marshall-Palmer size distribution (1948). In an effort to verify the simulated results, the data collected by the Airborne Second Generation Precipitation Radar (APR-2) in the Wakasa Bay AMSR-E campaign are employed. Using the signatures of Linear Depolarization Ratio (LDR) at Ku-band, the APR-2 data can be easily divided into the regions of snow, mixed phase and rain for stratiform storms. These results are then superimposed onto the theoretical curves computed from the model in the ZKu-DFR plane. It has been found that in 90% of the cases, snow and rain can be distinguished if the Ku-band radar reflectivity exceeds 18 dBZ (the minimum detectable level of GPM DPR at Ku-band). This is also the case for snow and mixed-phase hydrometeors. Although snow can be easily distinguished from rain and melting hydrometeors by using Ku- and Ka-band radar, the rain and mixed-phase particles are not always separable. It is concluded that Ku- and Ka-band dual-wavelength radar might provide a potential means to identify the phase state of hydrometeors.
41 citations
24 Jul 2011
TL;DR: Histogram, the incident angle dependence, and the geographical distribution of heavy rainfall events are shown and the reasons why rain rates are increased over land in going from V6 to V7 are discussed.
Abstract: The Tropical Rainfall Measuring Mission (TRMM) / Precipitation Radar (PR) has been working for more than 12 years, and the latest version (Version 7; V7 in short) of the standard product is published in 2011. A test product (called ITE233), which is essentially the same with the final product of V7, is compared with the previous version (Version 6; V6 in short). Generally, rain rate estimates are larger in V7 than in V6 both over land and over ocean. Histogram, the incident angle dependence, and the geographical distribution of heavy rainfall events are shown and the reasons why rain rates are increased over land in going from V6 to V7 are discussed.
13 citations