NUMERICAL STUDY OFTHE HAIL HAZARD OF DEVELOPING CONVECTIVE CLOUDS BY SCATTERED LIGHT DEPOLARIZATION BY CLOUD DROPS AND RAINDROPS

Introduction. Currently there are many works devoted to the problem of forecasting hail, based on the analysis of real stratification of the atmosphere, satellite and radar information. In recent years polarization methods have been significantly developed to study the clouds and precipitation structure. Materials and methods of the research. These methods are based on a change in the polarization of the reflected signal during scattering of radio waves by various particles of the clouds. One of the tools for such studies is a meteorological radar polarimeter with a working scattering angle of 90°. There are many works carried out using a radar polarimeter in the literature. Basically, these works are theoretical and experimental. Here we will try to conduct a numerical study of convective clouds for their hail hazard by scattering light scattered by cloud drops and raindrops at a scattering angle of 90°, to find the criterial number of depolarization for centimeter wavelengths. In this regard, this work is devoted to the study of convective clouds for specific stratifications of the atmosphere. Results of the study and their discussion. On the basis of the jet convection model, a numerical study of developing convective clouds for their hail hazard by the Mie functions for centimeter wavelengths was carried out. It was shown that the depolarization value is maximum at the scattering angle of 90° and is almost constant to a certain height in the cloud, and then decreases. Depolarization decreases in scattering forward and backward, tending to zero, for other values of the scattering angle. The values of the criterial numbers of depolarization at the scattering angle of 90° were obtained for the clouds in question as a first approximation. Conclusions. The possibility of determining the hail hazard of the cloud by the numerical depolarization method is considered, determining the criterial values of the scattered light depolarization by cloud drops and raindrops for given centimeter wavelengths. It was established that according to our calculations, the clouds in question are hail hazardous and their criterial number of depolarization is D₉₀ < 0,12. For a complete solution to this problem, an analysis of the calculations of many clouds is needed. The value of depolarization is maximum and almost constant at the scattering angle of 90° for the considered wavelengths. And for other values of the scattering angle, the depolarization decreases with scattering forward and backward, tending to zero.

scattered light depolarization, electromagnetic radiation, Mie scattering theory, Stokes parameters, intensity, polarization parameters, convective cloud model, scattered light polarization

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