Some factors affecting the remote sensing of rain by polarization diversity radar in the 3‐ to 35‐GHz frequency range

Abstract

Polarization diversity radars, both CDR and ZDR, are currently being used to investigate precipitation environments for meteorological and radio science purposes. Various frequencies are being used. This paper investigates the use of such radars for the remote sensing of rain, including the dependency of the various measurements on frequency, as well as on various model assumptions about the rain, such as drop shape, drop size distribution, water temperature, and canting angle distribution. The effect of rain occurring on the path between the radar and the rain target is also considered, and at S band propagation effects are clearly worse for CDR than for ZDR radars. It is clear that the use of frequencies above about 20 GHz for the purpose of rain measurement is very problematical.

A comparison of different polarization schemes for the radar sensing of precipitation

“…The details are given in the appendix. Equations (4) and (6) The elements of the transmission matrix M depend on the polarization scheme and are equal to, at linear H/V polarization mode [Holt, 1984] For circular polarization we observe that the diagonal elements of the matrix are the same. The off-diagonal elements are also the same except for a phase factor.…”

Radar measurement of rainfall by differential propagation phase: A pilot experiment

“…Since circular polarization is a combination of linear components, it is not surprising that linear parameters such as ZOR and fop may be extracted from the data obtained using the Alberta or Ottawa radar (Holt, 1988;McCormick, 1979). Though the extraction process is not exact, since it assumes that the raindrop canting angle is small, the value of Z DR obtained is not subject to error due to switching time.…”

“…In this situation, the polarization parameters can alter rapidly with size around the resonant drop size (e.g. Holt and Evans, 1977).…”

Polarisation basis transformation of weather radar measurements in the power domain

“…To quantify this influence, the scattering simulation was expanded. A raindrop canting angle α in the polarisation plane, Holt (1984), was included. The dependence of the reflectivities Z // , Z \\ and Z /\ on the raindrop canting angle α in the plane of polarisation is shown in Fig.…”