Composite anomalies of cyclone frequency (shading) and intrusion density (contours) for 30 warm extremes at lags (a) from −10 to −8, (b) from −8 to −6, (c) from −6 to −4, (d) from −4 to −2, and (e) from −2 to 0 days relative to peak warmth. For comparison, (f) climatological intrusion density plotted in the same units as in (a)–(e) is shown. Contours in (a)–(e) begin at 0.4 (thickest contour) and increase by 0.15. Dashed circles show the 70° and 80°N parallels.
Citation: Journal of Climate 31, 22; 10.1175/JCLI-D-18-0345.1