Changes in atmospheric circulation over the North Atlantic and sea-surge variations along the Belgian coast during the twentieth century

Wintertime (October-to-March period) 99th percentile of sea level (sea surges) at Ostend has increased at a rate of +3 mm/year (+1 mm/year) from 1925 to 2000. Relationships between daily sea surge at Ostend and five weather regimes Zonal (ZO), East Atlantic (EA), Greenland Above (GA), Blocking (BL), and Atlantic Ridge (AR) over the northeast Atlantic and Europe (40 degrees W-40 degrees E, 30 degrees-70 degrees N) are analysed during the period of 1925-2000. More than 70% of sea surges >= 65 cm occur during the AR weather regime, ahead of low pressure travelling on a northern track from Iceland to Scandinavia. The relationships between monthly/wintertime frequency of the AR weather regime and 99th percentile of sea surge at Ostend tend to strengthen during the twentieth century: for example, correlation between wintertime frequencies of AR and 99th percentile of sea surge increases from 0.21 in 1925-1950 to 0.74 in 1975-2000. This increase is associated with the pressure rise over the near Atlantic, between (30 degrees W and 15 degrees W), (30 degrees N and 50 degrees N), leading to an increase in the frequency of strong surge-related pressure gradient during AR days. Copyright (C) 2009 Royal Meteorological Societystatus: publishe