Methods for Assessing the State of Snow-Ice Cover

Abstract

The development new methods for measuring the electrophysical and geometric parameters multilayer dielectric medium in order to identify their layers, as well as to detect inhomogeneities in them, is an urgent scientific task. Methods for assessing the state the snow-ice cover are proposed, based on the identification layers of the snow-ice cover by the dielectric permittivity obtained indirectly as a result inclined sounding of the underlying surface by an electromagnetic wave with vertical and horizontal polarization. Under normal sensing the underlying surface, in the form snow-ice cover, by radio waves with vertical and horizontal polarization, the obtained values the reflection coefficient from the boundary layers the received signals are identical. Oblique sensing by a vertically polarized wave in the range from 25 to 90 degrees leads to a sharp dip in the values the reflection coefficient from the boundary layers at certain angles, so for dry snow – 47…55°, dry firn – 55 … 58° and dry ice – 58…61°. These angles characterize the dielectric properties the layers (permittivity), which are explained by the complete polarization the reflected wave in a plane perpendicular to the plane incidence, since at this moment the vibrations the layer's electrons along the direction their movement do not lead to the emission electromagnetic waves in the direction the reflected wave (absent). The given estimated values the complex relative permittivity snow-ice cover as two component medium air and ice at a temperature from minus one to minus forty degrees, or three component medium air, ice and water at zero temperature are a sample for establishing the identity the characteristic properties layers. The purpose this article is to develop methods for assessing the state snow-ice cover used in determining the possibility performing a safe landing a helicopter – type aircraft on an unprepared site with snow-ice cover based on the identification the obtained characteristics snow-ice cover layers based on the results radar sensing with calculated data