ANTARCTIC WIND INTENSIFICATION AS INFERRED FROM THE NCEP/NCAR REANALYSIS DATA

Abstract

NCEP/NCAR reanalysis data have been used to examine variations of the sea level pressure and of the surface wind speed in the Antarctic region from 1950 to 2019. The objective of the work was to identify changes and quantify long-term trends in these two major weather and climate elements. The analysis included time series of monthly mean values of the sea level pressure and of the surface wind speed as well as their yearly means. The study has shown a gradual decrease of the sea level pressure and a gradual increase of the surface wind speed in the high latitude region of the Southern Hemisphere in the last 70 years (1950–2019). The largest pressure decrease was within 65–70°S latitude band approximately corresponding to the location of the Antarctic Circumpolar Trough (ACT). The estimated trend in the yearly averaged sea level pressure ranged from –0.058 mb/yr over the open ocean north of ACT, within the 50–60°S latitude band, to –0.148 mb/yr over the Antarctic continent, within 65–85°S latitudes. The zonal-mean wind speed trends ranged within 0.020 m/s/yr and 0.026 m/s/yr over the continent and over the open ocean with up to the 3–4 times larger values in the coastal areas of East Antarctica. Seasonally larger changes in both parameters occurred in the cold period of the year from April to August. Trends in both the sea level pressure and in the wind speed in the Antarctic region were found to generally decelerate in the last decade covered by the dataset.