Effects of Solar Proton Events of January 2005 on the Middle Atmosphere Circulation in the Southern Hemisphere

In this paper, we study the effects of solar proton events (SPEs) of January 2005 on the stratosphere circulation in the Southern Hemisphere according to the NCEP-DOE (National Centers for Environmental Prediction-Department of Energy) reanalysis (R-2) data. It was found that in the course of the considered events, in the upper stratosphere (30-10 hPa), where eastern transport of air masses dominates in the whole hemisphere in summer season (December-February), eastern winds noticeably weakened at middle and high latitudes (> 40 degrees S), while they strengthened at lower latitudes. In the lower stratosphere (100-50 hPa), where circulation is characterized by a western zonal flow at middle latitudes, a weakening of eastern winds took place only in the polar region (> 60 degrees S), with a maximum of the western zonal flow being shifted to higher latitudes. The effects of SPEs of January 2005 observed in the stratosphere circulation of the Northern and Southern Hemispheres were compared. It has been shown that in the Northern (winter) Hemisphere the SPE effects observed in variations of zonal wind velocity are more pronounced than those in the Southern (summer) Hemisphere. It is supposed that the circulation disturbances, which were detected in both hemispheres during the studied SPEs, may be caused by changes in the temperature regime of the polar atmosphere due to variations in its chemical composition (ozone depletion) associated with a considerable increase in the ionization rate.