Fu, QiangWhite, Rachel HWang, MingchengAlexander, BeckySolomon, SusanGettelman, AndrewBattisti, DavidLin, Pu2020-01-242020-01-242020http://hdl.handle.net/1773/45025The Brewer-Dobson circulation (BDC) during the last glacial maximum (LGM) is investigated in simulations using the Whole Atmosphere Community Climate Model version 6 (WACCM6). We examine vertical mass fluxes, age of stratospheric air, and the transformed Eulerian mean stream function and find that the modeled annual-mean BDC during the LGM is almost everywhere slower than that in the modern climate (with or without anthropogenic ozone depleting substances). Compared to the modern climate, the annual-mean tropical upwelling in the LGM is 11.3-16.9%, 11.2-15.8%, and 4.4-10.2% weaker, respectively, at 100, 70, and 30 hPa. It is shown that the decrease in the annual-mean tropical upwelling at 70 hPa is caused by a weaker orographic gravity wave drag.en-USAttribution-NonCommercial-ShareAlike 3.0 United Stateshttp://creativecommons.org/licenses/by-nc-sa/3.0/us/Brewer-Dobson circulationlast glacial maximumorographic gravity wave dragWACCM6Article