[A-AS06] Stratosphere-troposphere Processes And their Role in Climate

[AAS06-05] Stratospheric Influence on the Troposphere During the Remarkably Strong Arctic Circumpolar Vortex Condition in 2019-2020 Winter

*Shunsuke Noguchi^1,2, Kunihiko Kodera², Ryo Mizuta², Seiji Yukimoto² (1.Japan Agency for Marine-Earth Science and Technology, 2.Meteorological Research Institute)

Keywords:Stratosphere-Troposphere Coupling, Arctic Ozone Depletion, Arctic Oscillation/Northern Annular Mode

Tropospheric responses to the remarkably strong stratospheric polar vortex condition in 2019-2020 Arctic winter and spring have been investigated by conducting a series of ensemble forecast experiments. In particular, by conducting ensemble "nudged" integrations, whose stratospheric circulation is relaxed toward a reanalysis, and comparing them with reference ensemble integrations, we deduce a significant effect of the stratosphere on the culmination of the anomalous circulation pattern characterized by a positive phase of the Arctic Oscillation. Various factors that led to the formation of anomalies in the stratosphere and troposphere during this extreme season will also be discussed through comparisons between the experiments and additional experiments.