Atmospheric Dynamics Leading to West European Summer Hot Temperatures Since 1851

Figure 2

Relative long-term summer weather regime frequency. Relative frequency of summer SLP (hPa) weather regimes over the North-Atlantic region (1851–2014) using 20CRv2c. Here we show SLP anomalies with respect to the reference period 1970–2010 for each (a)–(d) and all (e) weather regimes; solid lines in (a)–(d) represent the linear trend for each regime. 1930 is marked with a vertical dashed line.

(a) NAO−

(b) AR

(c) BLO

(d) AL

(e) 4 Weather regimes