Southern-Hemisphere high-latitude stratospheric warming revisit

Abstract

AbstractPrevious studies showed significant stratospheric warming at the Southern-Hemisphere (SH) high latitudes in September and October over 1979–2006. The warming trend center was located over the Southern Ocean poleward of the Western Pacific in September, with a maximum trend of about 2.8 K/decade. The warming trends in October showed a dipole pattern, with the warming center over the Ross and Amundsen Sea, and the maximum warming trend is about 2.6 K/decade. In the present study, we revisit the problem of the SH stratospheric warming in the recent decade. It is found that the SH high-latitude stratosphere continued warming in September and October over 2007–2017, but with very different spatial patterns. Multiple linear regression demonstrates that ozone increases play an important role in the SH high-latitude stratospheric warming in September and November, while the changes in the Brewer-Dobson circulation contributes little to the warming. This is different from the situation over 1979–2006 when the SH high-latitude stratospheric warming was mainly caused by the strengthening of the Brewer-Dobson circulation and the eastward shift of the warming center. Simulations forced with observed ozone changes over 2007–2017 shows warming trends, suggesting that the observed warming trends over 2007–2017 are at least partly due to ozone recovery. The warming trends due to ozone recovery have important implications for stratospheric, tropospheric and surface climates on SH.