A blocking view of the stratosphere-troposphere coupling

摘要: Dynamical influence from the stratosphere is known to play a role in shaping wintertime tropospheric circulation patterns. Observations suggest that this strongest following weak and strong polar vortex events, termed sudden stratospheric warmings (SSWs) intensification (VI) respectively. In work, stratosphere-troposphere coupling studied through modulation by extreme events of Northern Hemispheric blocking frequency eddy-driven jet displacements. This done using three reanalysis data sets Centro Euro-Mediterraneo sui Cambiamenti Climatici Climate Model with resolved Stratosphere (CMCC-CMS) coupled model control run. Reanalysis results existence distinct patterns activity events. Over Atlantic basin, SSWs are shown lead about 20–50 days occurrence increased/reduced on poleward/equatorward side stream. Anomalies opposite sense, poleward reduction equatorward enhancement frequency, occur VI The response over Pacific sector less clear. Compared reanalyses, CMCC-CMS shows similar but weaker response, especially Atlantic: possible explanation identified different structure wind shear anomalies respect reanalysis. We finally highlight extremes show similarities Annular Mode not Pacific. suggests more regional than annular feature.