Features of Microwave Measurements of Cryospheric Formations Using UAVs

Abstract

The paper presents the results of remote studies of cryospheric formations in the microwave range using unmanned aerial vehicles (UAVs). For these purposes, a radiometric receiver with a frequency of 34 GHz with a bandwidth of 2.3 GHz with a fluctuation sensitivity of 0.05 K at a time constant of 1 s was installed on board the UAV. The directional pattern of the corrugated antenna was about 10°. It is shown that this method of monitoring in the millimeter range of media containing ice inclusions is an urgent task, especially in hard-to-reach places. There are a number of difficulties in interpreting the obtained brightness temperature of the radiating medium, which characterizes the power of thermal radiation. The first difficulty lies in the fact that the obtained value of this temperature depends on the angle of observation, therefore, at the time of radiometric studies of cryospheric formations, it is necessary to measure the position of the UAV in space (pitch and roll angles). In addition, it is necessary to take into account the terrain, namely the angles of its inclination relative to the horizon. The second difficulty in interpreting the data obtained from microwave measurements of thermal radiation power is the peculiarity of the medium under study. For example, for a plane-layered three-layer medium with a relatively thin intermediate layer, interference of the brightness temperature is observed, both on vertical and horizontal polarization. Inclusions in cryospheric formations with sharply different dielectric characteristics from the medium itself, for example, gas bubbles in ice, should also be taken into account. The work will be of interest to researchers involved in monitoring various cryospheric environments, both for practical (ice crossings) and scientific (glaciers) purposes.