LONG-TERM VARIABILITY OF FREE-ATMOSPHERE TEMPERATURE IN THE SOUTH POLAR REGION

G. V. Gruza, V. V. Maistrova, I. I. Bolshakova, and O. L. Zhukova

Analysis of interannual temperature variability in the South Polar Region (54—90ºS) over the period 1959—2003 based on empirical observations is indicative of warming in the layer 850—300 hPa. Annual mean temperature series at all pressure levels in this layer show positive trends statistically significant at the 1% level. Maximum warming for all seasons was in the layer 500—400 hPa. A summer temperature rise at 500 hPa was 2.4ºC. Above 300 hPa, there was a temperature decrease, but a 1% significant decrease in annual temperature was only in the layer 100—70 hPa. Over the given period, the annual temperature at 100 hPa decreased by 2.3ºC. Seasonal temperature changes, except for those in summer, are dominated by negative trends. In winter, negative trends are statistically significant at all levels, and a maximum decrease (4.5ºC) was at 100 hPa. In summer, the trends were positive and statistically significant at all levels from 850 to 150 hPa.