Fig. 2: Linkage between heatwaves and atmospheric teleconnections (AT).
Composite anomalies of (a, d) air temperature at 2 m (\({T}_{2m}\); shadings; units: K) and atmospheric circulations at 500 hPa (UV500; vectors; units: m s-1), and (b, e) geopotential height (H500; shadings; units: gpm) and wave flux activity (WAF500; vectors; units: m2 s-2) at 500 hPa. a, b are the composite anomalies for Eastern European heatwave events, while (d, e) are for Western European heatwave events. Cross-degree centrality of high-pressure extremes (shadings; units:×1000) inside (c) Eastern European heatwaves and (f) Western European heatwaves. Cross-degree centrality of low-pressure extremes (blue dashed contours) for Eastern European heatwaves (shown at 42,000 and 50,000) and Western European heatwaves (shown at 21,000 and 25,000) are also plotted in (c) and (f), respectively. g Explained variance (\({R}^{2}\)) of yearly heatwave cumulative intensity (HWI) by AT, and h the zonal median in explained variance (red solid line). \(R\) is the correlation coefficient between the yearly detrended time series of HWI and AT at each grid cell. The zonal median in explained variance between HWI and similar AT index using only local high-pressure intensities is also plotted as orange dashed line in (h). Significant values (\(p < 0.05\)) are hatched and insignificant vectors are not plotted in (a, b) and (d, e). The wave activity fluxes are not shown when both directions of the values are less than 0.5 m2 s-2 or both wind component (\(u\) and \(v\)) anomalies are insignificant. The red dashed lines in (a) and (d) denote the regions that are 2700 km and 5200 km far away from the centers of Eastern and Western European land areas, respectively. Yearly explained variances in (g) are positive over all grid cells and significant (\({R}^{2} > 0.147,{p} < 0.01\)) over 99.8% of the land areas.
