Showing papers by "Robert Meneghini published in 1994"
TL;DR: In this paper, a review of single-frequency rain profiling methods for an airborne or spaceborne radar is presented starting from a unified point of view starting from the basic differential equation, which facilitates the comparisons between the methods and also provides a better understanding of the physical and mathematical basis of the methods.
Abstract: This paper briefly reviews several single-frequency rain profiling methods for an airborne or spaceborne radar. The authors describe the different methods from a unified point of view starting from the basic differential equation. This facilitates the comparisons between the methods and also provides a better understanding of the physical and mathematical basis of the methods. The application of several methods to airborne radar data taken during the Convective and Precipitation/Electrification Experiment is shown. Finally, the authors consider a hybrid method that provides a smooth transition between the Hitschfeld-Bordan method, which performs well at low attenuations, and the surface reference method, for which the relative error decreases with increasing path attenuation.
252 citations
TL;DR: Airborne microwave measurements of precipitation associated with Super Typhoon Flo in the western North Pacific were conducted during September 16-18, 1990 and it was shown from a close examination of both active and passive microwave signatures that a significant scattering of radiation at frequencies 118 GHz occurred in the inner eyewall at altitudes of 3-8 km.
Abstract: Airborne microwave measurements of precipitation associated with Super Typhoon Flo in the western North Pacific were conducted during September 16-18, 1990 The sensor package aboard the NASA DC-8 aircraft included a dual-frequency precipitation radar at 10 GHz and 34 GHz and a host of radiometers operating at 10 GHz, 18 GHz, 19 GHz, 34 GHz, and 92 GHz, as well as three frequencies near the strong water vapor absorption line of 1833 GHz The measurements were made during a few passes over the storm center, and active and passive microwave signatures of the rainbands were detected with a fine spatial resolution The relationship between the measured brightness temperature and radar-estimated rain rate is examined at the frequencies between 10-92 GHz At both 34 and 92 GHz this relationship is analyzed with the 10 GHz radar reflectivity factor measured at altitudes above the freezing layer as a further constraint The results show that frozen hydrometeors strongly scatter radiation at these frequencies, especially at 92 GHz It was shown from a close examination of both active and passive microwave signatures that a significant scattering of radiation at frequencies 118 GHz occurred in the inner eyewall at altitudes of 3-8 km This scattering of microwave radiation by hydrometeors in both liquid and frozen forms is discussed under the authors' current understanding of the scattering mechanism >
25 citations
TL;DR: In this article, the vertical profiles of the linear depolarization ratio, LDR (10 GHz), the reflectivity factor, dBZ(10 GHz); and the dual-frequency ratio, DFR (10, 34.45 GHz) were analyzed for measurements taken in stratiform rain in the western Pacific during September 1990.
Abstract: Airborne dual-wavelength and dual-polarization radar data are analyzed for measurements taken in stratiform rain in the western Pacific during September 1990. The focus of the paper is on the vertical profiles of the linear depolarization ratio, LDR (10 GHz); the reflectivity factor, dBZ (10 GHz); and the dual-frequency ratio, DFR (10, 34.45 GHz). Statistical characterizations of the maxima of these quantities and the relative locations at which they occur suggest that the eccentricity of the melting particles is fairly large and that the shape and size of the particles are correlated. To try to explain these features, two types of simulation are presented. In the first, a set of measured drop size distributions is used in the context of a standard model of the melting layer. Variations in snow density, as well as shape, size, and orientation distributions are used to study the relationship between these parameters and the radar measurements. To reduce the amount of ambiguity in the estimation, a second type of simulation is described in which the size distribution of the snow is estimated. Comparisons between the simulated and measured profiles indicate that radar measurements can be used to derive certain characteristics of the particle size and shape distributions in the melting layer.
17 citations
08 Aug 1994
TL;DR: In this paper, a combined dual-wavelength radar and radiometer method is described for estimation of precipitation parameters from airborne or spaceborne platforms, where the idea of the method is to identify a number of drop size distributions that are consistent with the radar measurements and then to narrow the number of possible solutions by using the results to regenerate the measured radar and radometric responses.
Abstract: A combined dual-wavelength radar and radiometer method is described for estimation of precipitation parameters from airborne or spaceborne platforms. The idea of the method is to identify a number of drop size distributions that are consistent with the radar measurements and then to narrow the number of possible solutions by using the results to regenerate the measured radar and radiometric responses. After showing simulation results to highlight the advantages and defects of the method, application is made to airborne radar/radiometer measurements over stratiform precipitation measured in the Western Pacific. >
8 citations