Weakening of Antarctic Stratospheric Planetary Wave Activities in Early Austral Spring Since the Early 2000s: A Response to Sea Surface Temperature Trends

Abstract

Abstract. Using multiple reanalysis datasets and modeling simulations, the trends of Antarctic stratospheric planetary wave activities in early austral spring since the early 2000s are investigated in this study. We find that the stratospheric planetary wave activities in September have weakened significantly since 2000, which is related to the weakening of the tropospheric wave sources in the extratropical southern hemisphere. Further analysis indicates that the trend of September sea surface temperature (SST) over 20° N–70° S is statistically linked to the weakening of stratospheric planetary wave activities. Numerical simulations support the result that the SST trend in the extratropical southern hemisphere (20° S–70° S) and the tropics (20° N–20° S) induce the weakening of wave-1 component of tropospheric geopotential height in the extratropical southern hemisphere, which subsequently leads to the decrease in stratospheric wave flux. The responses of stratospheric wave activities in the southern hemisphere to stratospheric ozone recovery is not significant in simulations. In addition, both reanalysis data and numerical simulations indicate that the Brewer-Dobson circulation (BDC) related to wave activities in the stratosphere has also been weakening in early austral spring since 2000 due to the trend of September SST in the tropics and extratropical southern hemisphere.