Study on the impact of sudden stratosphere warming in the upper mesosphere-lower thermosphere regions using satellite and HF radar measurements

摘要

The occurrence of a sudden stratospheric warming (SSW) excites disturbancesin the mesosphere-lower thermospheric (MLT) wind and temperature. Here, wehave examined the high frequency (HF) radar wind data from the South AfricanNational Antarctic Expedition, SANAE (72° S, 3° W), a radar which ispart of the Super Dual Auroral Radar Network (SuperDARN). Sounding of theAtmosphere using Broadband Emission Radiometry (SABER) on board theThermosphere-Ionosphere-Mesosphere-Energetics and Dynamics (TIMED)satellite temperature data and National Centre for Environmental Prediction(NCEP) temperature and wind data are used to investigate the dynamicaleffects of the unprecedented September 2002 SSW in the Antarcticastratosphere and MLT. The mean zonal wind (from SANAE HF radar) at the MLTshows reversal approximately 7 days before the reversal at 10 hPa (fromNCEP). This indicates that there was a downwards propagation of circulationdisturbance. Westerly zonal winds dominate the winter MLT, but during the2002 winter there are many periods of westward winds observed compared toother years. The normalised power spectrums of both meridional and zonalwinds show presence of planetary waves (of ~14-day period) before theoccurrence of the SSW. The SABER vertical temperature profiles indicated thecooling of the MLT region before the SSW event.