Atmospheric Dynamics Leading to West European Summer Hot Temperatures Since 1851

Figure 4

Changes in the dynamical representation of the warmest summers. (a, b) Average correlations of warmest summers with respect to the 4 weather regimes (black circle on -axis in Figure 3), points represent each member, crosses represent the mean of all the 56 members, and circles represent the EM. Colors represent the 4 groups of summers (G1 red, G2 purple, G3 green, and G4 blue). In (c)–(f), boxplots show frequencies of the 4 weather regimes classified in two periods: (c, e) for summers before 1930 (groups G1 + G2) and (d, f) for summers after 1930 (groups G3 + G4), for all the 56 members (c, d) and the EM (e, f). (g) shows the difference in the SLP mean between those two periods (after 1930 and before 1930). Points represent significance at 95 percent after the performance of a Monte Carlo test.