Fig. 4: The atmospheric circulation associated with the VM index.

a Regressed anomalous pattern of DJFMAM 200 hPa geopotential height (shading; units: m) and horizontal winds (vectors; units: m s–1) with respect to the VM index. b As a but for 850 hPa. Areas with regression significant at the 95% level are shown. The wind anomalies are shown only when the zonal or meridional wind anomalies are significant at the 95% confidence level. Boxes indicate the domain to represent mid-to-high-latitude eastern Eurasia and eastern North America, respectively.