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For any quantitative applications that use reflectivity and/or differential reflectivity, radar observations need to be compensated for attenuation effects due to precipitation. This paper presents a robust attenuation correction system (ACS) for dual-polarization radars correcting the reflectivity factor as well as differential reflectivity profiles. The major advantage of the algorithm described in this paper is that the procedures are immune to the bias effect of reflectivity and differential reflectivity. In addition, this method is not very sensitive to the variation of temperature. The proposed ACS has been evaluated with X-band radar observations simulated from drop size distribution derived from high-resolution S-band measurements observed by the CSU-CHILL radar. The evaluation of the proposed retrieval algorithm shows that the retrieved reflectivity and differential reflectivity provide an improvement over the conventional self-consistent attenuation correction technique with the differential phase constraint. [ABSTRACT FROM PUBLISHER]

This paper focuses on a dual-wavelength technique to detect hail in convective cells from a weather airborne radar. The topic is of great interest since hailstorm is the main meteorological hazard in the context of civil aviation. Considering S, C, and X frequency bands, the question of the most efficient frequency couple is addressed by means of simulations of airborne radar observations. A convective system made of two successive rows of convective towers is first modeled. Another one extracted from a real hailstorm is then considered. It is shown that the quantity dy/dr, where r is the radial coordinate along the ray path and y is the measured differential reflectivity at two different wavelengths, is a good indicator of hail areas. This quantity, associated with the measured reflectivity at the less attenuated wavelength (i.e., the longest one), enables one to identify convective cells containing hail. It appears that the frequency couples S-X and C-X are the best ones for hail detection. In the context of civil aviation, the second one (C-X) permits one to minimize antenna size. [ABSTRACT FROM PUBLISHER]

A method is described for adjusting the far-field polarization of an electronically steered phased-array antenna. In this method, the polarization of a small subset of array elements is switched in order to reduce far-field cross-polarization of the overall array. The technique is intended for antennas used in polarimetric radars that measure quantities such as differential reflectivity (Zdr) and specific differential phase (KDP). In particular, it is appropriate for lower cost arrays where only one transmit or receive polarization is active at a time. In such arrays, it will reduce the number of measurements needed by one-third. Analysis of the tradeoffs in the technique is presented as well as examples in hypothetical large arrays. Measured results are presented for a small 4×4 array. [ABSTRACT FROM AUTHOR]