Recent Trends in the Recurrence of North Atlantic Atmospheric Circulation Patterns

Figure 2

(a) Four weather regimes of SLP anomalies in DJF (negative phase of the NAO, Atlantic Ridge, Scandinavian Blocking, zonal flow). The isolines have increments of 2 hPa. (b) Trends in atmospheric persistence for DJF. Vertical colored lines: frequency of dominating weather regime. The color is associated with a weather regime (NAO−: black; AR: red; BLO: green; ZO: blue). Gray dotted line: linear trend of regime frequencies. Continuous back lines: frequency of dominating network in the winter. Dashed black lines: linear trend of dominating network frequency. Vertical dash-dotted lines are for the five years with the largest numbers of similar days (1969, 1989, 1990, 2010, and 2014).

(a)

(b)