Fig. 3
From: The different stratospheric influence on cold-extremes in Eurasia and North America
Composites of temporal evolution of different standardized stratospheric indices 20 days prior and after cluster 4 events (left column) and cluster 5 events (right column). a, b The P4 and P5 index (light green shading), and the polar cap height mean index PCH at 10 hPa (green line). c, d The hemisphere-averaged vertical wave-activity flux (WAFHem, red shading) and the regional index of vertical wave-activity flux over the Euro-Atlantic sector (WAFEuro-Atl, red line). e, f Regional indices of vertical wave-activity flux over eastern Siberia (WAFsiberia, pink shading) and Canada (WAFCanada, brown line). In all panels, significant values (p < 0.05, see Methods) are indicated with dots
