Fig. 3: Impact of stratospheric water vapor differences on near–surface circulation.

a Zonal mean zonal wind on 850 hPa pressure surface during boreal summer (June–August) from the control and the new Lagrangian modified EMAC–CLaMS simulation (black lines), with stratospheric water vapor in the Lagrangian simulation substantially reduced, and the difference “control” minus “modified” (red line). Error bars show 2-σ standard error range related to year-to-year variability, and regions with changes being significant at 95% confidence level are marked with red coloring of the base line. b Difference map of zonal wind on 850 hPa between control and Lagrangian modified EMAC–CLaMS simulation for boreal summer. Black contours show the zonal wind reference climatology from control EMAC. Dotted regions indicate non-significant changes compared to year-to-year variability (at 95% confidence level). c, d Same, but for boreal winter season (December–February).