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The role of large‐scale atmospheric flow and Rossby wave breaking in the evolution of extreme windstorms over Europe
Author(s) -
Hanley John,
Caballero Rodrigo
Publication year - 2012
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2012gl053408
Subject(s) - rossby wave , anticyclone , storm , climatology , baroclinity , geology , zonal flow (plasma) , atmospheric circulation , extratropical cyclone , winter storm , oceanography , physics , plasma , quantum mechanics , tokamak
We investigate the relationship between large‐scale atmospheric flow and the evolution of the most extreme windstorms affecting Western Continental Europe. The 25 most destructive Western Continental European wind storms are selected from a 43‐year climatology. 22 of these storms are grouped as having a similar trajectory and evolution. We show that these storms typically occur during particularly strong and persistent positive NAO anomalies which peak approximately 2 days before the storms' peak intensity; the NAO pattern then shifts eastward to a position over the European continent when the storms strike Europe. A temporal composite of potential temperature on the 2‐PVU surface suggests that this NAO shift is the result of simultaneous cyclonic and anticyclonic wave breaking penetrating further to the east than during a typical high‐NAO event. This creates an extremely intense, zonally‐orientated jet over the North Atlantic whose baroclinicity favours explosive intensification of storms while steering them into Western Continental Europe.