Fig. 2: Atmospheric circulation effects and dynamical mechanism induced by lowermost stratospheric water vapor changes.

A, E Temperature differences between control minus Lagrangian modified EMAC–CLaMS simulations are shown for boreal winter (December–February, top) and summer (June–August, bottom). Climatological temperatures from the control simulation are shown as gray contours, the WMO lapse rate tropopause as black line (for CMIP6 and CCMI2 calculated from ERA5 reanalysis). The same is shown for (B, F) zonal wind, (C, G) residual circulation vertical velocity \({\overline{w}}^{*}\), D, H resolved wave forcing quantified in terms of Eliassen-Palm flux divergence. For the latter variables, zonal wind contours from control simulation are shown as white lines. Dots indicate non-significant changes compared to year-to-year variability (at 95% confidence level).