Changes in Brewer–Dobson Circulation Seen from Satellite MSU/AMSU Observations

We examine the Brewer-Dobson circulation (BDC) changes based on satellite Microwave Sounding Unit (MSU/AMSU) lower-stratospheric temperature (T_LS) observations and ERA-Interim reanalysis data. We consider the entire period of 1980-2018, as well as the ozone depletion (1980-1999) and ozone healing (2000-2018) periods. We provide observational evidence that the annual mean BDC accelerated for 1980-1999 but decelerated for 2000-2018, with the changes largely occurring in the Southern Hemisphere (SH). We also show that the annual mean BDC has accelerated in the last 40 years (at the 90% confidence level) with a relative strengthening of ~1.7% per decade. This overall acceleration was driven by both Northern Hemisphere (NH) (40%) and SH (60%) cells. Significant SH radiative warming is identified in September for 2000-2018, supporting the view that healing of the Antarctic ozone layer has now begun to occur during the month of September.