%0 Journal Article
%A Yessimbet, Kamilya
%A Shepherd, Theodore G.
%A Ossó, Albert C.
%A Steiner, Andrea K.
%T Pathways of Influence Between Northern Hemisphere Blocking and Stratospheric Polar Vortex Variability
%J Geophysical research letters
%V 49
%N 23
%@ 0094-8276
%C Hoboken, NJ
%I Wiley
%M FZJ-2023-00411
%P e2022GL100895
%D 2022
%X We apply a causal inference-based framework to test and quantify previously suggested causalrelationships between Northern Hemisphere blocking, upward wave-activity fluxes and stratospheric polarvortex (SPV) variability using reanalysis data. We show that the influence of blocking on the polar vortex isentirely mediated by upward wave-activity fluxes, as the classical view would suggest. However, the causalpathway is not completely straightforward. In contrast to the vortex-weakening effect of European blocking,the vortex-strengthening effect of west Pacific blocking on lower stratospheric wave-activity fluxes is onlypartially mediated by upper tropospheric wave-activity fluxes. In addition, only two-thirds of the effectof upper tropospheric wave-activity fluxes on polar vortex variability is mediated by lower stratosphericwave-activity fluxes. We also show that sudden stratospheric warmings are not entirely explainable in terms ofupward wave-activity fluxes. These findings help clarify the pathways of influence between blocking and SPVvariability.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000928052000028
%R 10.1029/2022GL100895
%U https://juser.fz-juelich.de/record/917179