Satellite Microwave Radiometric Measurements of Extreme Temperature Rise in East Antarctica in March 2022

Abstract

The results of sensing of East Antarctica and the adjoining areas of the Southern Ocean by MTVZA-GYа microwave satellite radiometers at frequency ν = 10–190 GHz and AMSR2 at ν = 6–89 GHz in conditions of warm and humid air (an atmospheric river (AR)) invasion from the area of Tasmania area in March 2022 are presented. The surface air warming caused by AR was recorded by the Automatic Weather Station at the coast and at the Vostok, Concordia, and Dome CII stations in East Antarctica. The variability of atmospheric characteristics above Antarctica was studied using readings of radiosondes launched from the Casey station at the coast and Concordia station at a height of 3230 m and time series of brightness temperatures averaged over a circular area 200 km in diameter with the center at a distance of ~200 km from the Concordia station. The influence of air and surface temperature and atmospheric water-vapor content variations on brightness temperature T_b(ν) variations was estimated from the results of modeling of microwave radiation transfer in the atmosphere–firn system using radiosonde profiles from the Concordia station. It was shown that the increase in T_b(ν) at frequencies of 89–92 GHz of a large part of East Antarctica was caused mainly by an increase in the firn temperature. The increase at frequencies of ∼176–190 GHz in the area of the water vapor absorption line was caused by an increase of both the firn temperature and air temperature and humidity. Based on measurements of brightness temperature T_b(ν) over the open ocean at frequencies in the atmospheric-transparency windows of ∼6–48 and 88–92 GHz, wind speed W, cloud liquid-water content Q, and atmospheric water-vapor content V were determined and the temporal variability of parameters in the AR area was studied.