Showing papers by "Robert Meneghini published in 2012"

Assessment of the Performance of a Dual-Frequency Surface Reference Technique Over Ocean

Abstract: The high correlation of the rain-free surface cross sections at two frequencies suggests that the estimate of differential path-integrated attenuation caused by precipitation along the radar beam can be obtained to a higher degree of accuracy than the path attenuation at either frequency. We explore this potential first analytically and then by examining data from the JPL dual-frequency airborne radar using measurements from the Tropical Composition, Cloud, and Climate Coupling experiment obtained during July-August 2007. Despite an improvement in the accuracy of the differential path attenuation, solving for parameters of the particle size distribution often requires not only this quantity but the single-wavelength path attenuation as well. We investigate a simple method of estimating the single-frequency path attenuation from the differential attenuation and compare this estimate with that derived directly from the surface return.

An overview of the precipitation retrieval algorithm for the dual-frequency precipitation radar (DPR) on the global precipitation measurement (GPM) mission's core satellite

Abstract: This paper describes the planned level 2 algorithm that retrieves precipitation profiles from data to be obtained by the Dual-frequency Precipitation Radar (DPR) on the core satellite of the Global Precipitation Measurement (GPM) mission. The general idea behind the algorithms is to determine general characteristics of the precipitation, correct for attenuation and estimate profiles of the precipitation water content, rainfall rate and, when dual-wavelength data are available, information on the particle size distributions in rain and snow. It is particularly important that dual-wavelength data will provide better estimates of rainfall and snowfall rates than the TRMM PR data by using the particle size information and the capability of estimating the height at which the precipitation transitions from solid to liquid.

Using surface classification to improve surface reference technique performance over land

Abstract: The surface reference technique (SRT) is the primary method of estimating atmospheric attenuation for spaceborne rain radars. The authors hypothesize that part of the error in applying the along-track spatial SRT over land is due to the difference in land type between the reference area and the rain area. Tropical Rainfall Measuring Mission Precipitation Radar (TRMM PR) data is used to show that dividing the data into classes (unsupervised clustering) reduces the standard deviation of surface backscatter, especially near nadir incidence. Similar clustering at Ka-band is also found for a small set of aircraft data. These results are applied to the SRT by creating a new, class-based SRT in which a reference is maintained for each land class. The new SRT is shown to have smaller difference between forward and backward runs (a measure of the error), as compared with the standard (one-class) SRT, especially near nadir.