Attenuation and reflection of radio waves by a melting layer of precipitation

Abstract

Attenuation and reflection of a melting layer are calculated using a meteorological model. The model employs a new scheme for the calculation of the dielectric properties of melting ice particles with densities ranging from those of loose snow to hail, and a new scheme for calculating the melting rate is employed. The input parameters are derived from high resolution Doppler radar data and provide a data set for statistical analysis. Statistical relations were derived for attenuation in the melting layer based on measurements made with a surface rain gauge, a radar (with and without a polarisation facility), and a lower frequency satellite link. It was found that the specific attenuation of melting snow surpasses the value of rain because of the larger size and particle number density during melting, the attenuation within the melting layer increasing with its reflection. In stratiform precipitation, the attenuation in the melting layer is found to increase only slightly with frequency. The reflection in the melting layer decreases with the frequency of the radio waves in such a way that a bright band is only observed for frequencies below 20 GHz.

Backscattering by and propagation through the melting layer of precipitation: a new polarimetric model

“…eCPA increases almost linearly with the rain intensity, and becomes approximately 2 dB at 20 mmh. The predicted values are in good agreement with the calculations of [19], which are based on the Mie theory, whereas the present model uses the extended Rayleigh approximation. eCPD is very small: less than 0.2 dB.…”

Modeling of radiowave scattering in the melting layer of precipitation

“…Finally, radar and propagation parameters are, respectively, deduced from the total radar cross section (6) and (7) and the total extinction cross section (8) mm m (6) dB (7) db km (8) is the equivalent radar reflectivity factor in horizontal or vertical polarization, is the differential reflectivity, and is the specific attenuation.…”

“…The first application concerns the comparison between the CFPS model and three other models, developed in the framework of the Olympus propagation experiment (OPEX) by the European Space Agency (ESA), Noordwijk, The Netherlands [6], the University of Delft, Delft, The Netherlands [5], and the University of Helsinki (HUT), Helsinki, Finland [4]. The second application deals with determining an inversion process in order to invert the CFPS model and retrieve characteristics of the melting layer starting from radar data.…”

Microwave thawing of cylinders

“…cryosphere (Vant et al, 1978;Matzler and Wegmuller, 1987) and attenuation of radar signals in the atmosphere (Sihvola, 1989;Klassen, 1990). Thawing rates for frozen samples depend on the sample's material properties and dimensions and the magnitude and frequency of the electromagnetic radiation.…”