Brewer-Dobson circulation changes in Chemistry Climate models: shallow versus deep cells

We analyzed the simulated Brewer-Dobson circulation (BDC) from 12 Chemistry Climate models for 1960-2099, and decomposed the BDC into shallow and deep cells as well as northern and southern cells. Acceleration of both shallow and deep cells is seen in all models over the 140 years, but the acceleration rate in the shallow cells is much stronger. The BDC acceleration intensifies over time except for the southern deep cell, and distributes fairly evenly among seasons and between the two hemispheres. The effect on the BDC from changes in ozone concentration is manifested in the southern deep cell during austral summer: almost all models simulated strong significant acceleration during the ozone depletion era, weak deceleration during the ozone recovery era and near-zero trends during the ozone stabilization era. However, the ozone effect is not evident in other seasons and in other cells. Instead, continuous BDC strengthening is seen as greenhouse gases concentrations increase.