Authors: J A Santos J CorteReal U Ulbrich J Palutikof
Publish Date: 2006/06/14
Volume: 87, Issue: 1-4, Pages: 85-102
Abstract
The physical coupling between the occurrence of winter heavy precipitation in Europe and the surface largescale circulation is studied by isolating their coupled modes with a singular value decomposition technique The leading mode is a clear manifestation of the North Atlantic Oscillation forcing The second mode reflects the influence of a centreofaction in the pressure field westward of the British Isles The Hadley Centre Coupled Model 3rd generation is skilful in reproducing these two modes and an eastward extension of the North Atlantic Oscillation towards the Mediterranean Basin is projected under two future climatic scenarios This extension yields an increase in the North Atlantic Oscillation forcing over the occurrence of heavy precipitation in several regions of Southern Europe which is corroborated by the changes in the coupling of the daily precipitation A combination of the first six coupled modes of the daily precipitation revealed that its amounts in some parts of Western Europe and the Mediterranean are effectively governed by the largescale circulation The model is still reasonably skilful in reproducing this largescale coupling The projected modifications both in the strength and in the patterns of the coupled modes explain important fractions of the projected changes in variance which ultimately have implications in the occurrence of heavy precipitation in several European areas Therefore the ability of a model in reproducing the largescale forcing over the daily precipitation is important for the reliability of its projections of the occurrence of heavy precipitation in Europe
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