Seasonal evolution of the polar vortex and wave activity over Siberia

Zcap, WAFz midlatitude, and NAO index

Top : Polar cap geopotential (shading, m), and vertical component of Plumb wave activity flux (red/blue contours).

Bottom : daily North Atlantic Oscillation index (NAO, std deviation)

Polar_Vortex_temperature_ncep2_2020

WAFZ100-midlat-sib_ncep2_2020

MHF100-zonmean_ncep2_2020

UBI_ncep2_2020

December-January

February-March

Top left : polar vortex temperature (10 hPa). Red : current year ; Black and envelope : 1981-2010 climatology +/-2 std deviations

Top right : same, but for cumulative upward Plumb wave activity flux at 100 hPa averaged over Siberia

Bottom left : same, but for meridional heat flux at 100 hPa (zonal average)

Bottom right : Ural Blocking Index (normalized index of Z500 averaged over the 10W/80E ; 45/80N domain)