Shortages of winter rainfall over southern Europe precede hot summers further north on the continent, a new study shows.
From an analysis of meteorological records spanning the past 58 years, Vautard et al. determine that parched conditions around the northern Mediterranean create a mass of anomalously warm, dry air that spreads northward in early summer.
The researchers detected the pattern while searching for previously undiscovered weather scenarios that could help explain heat waves such as the one experienced by Europe in the summer of 2003. That hot spell severely impacted human health, vegetation productivity, and air quality.
Many models predict a boost in frequency of extreme weather events, such as heat waves, as human influence on climate grows. Because dry soil inhibits convective cloud formation, the authors suggest that soil water contents in Europe's Mediterranean regions play a critical role in the maintenance of climate across Europe. Numerical-simulation experiments of regional atmospheric circulation support that conclusion.
The investigators also find that previous winter and early spring rainfall frequency in the Mediterranean regions correlates with summer temperature in continental Europe.
Title: Summertime European heat and drought waves induced by wintertime Mediterranean rainfall deficit
Authors: R. Vautard: Laboratoire des Sciences du Climat et de l'Environnment, L'Institut Pierre-Simon Laplace, Gif sur Yvette, France; and Laboratoire de Météorologie Dynamique, École Polytechnique, Palaiseau, France; P. Yiou, N. de Noblet, N. Viovy, P. Ciais, and M. Kageyama: Laboratoire des Sciences du Climat et de l’ Environnment, L'Institut Pierre-Simon Laplace, Gif sur Yvette, France; F. D’Andrea and J. Polcher: Laboratoire de Météorologie Dynamique, École Polytechnique, Palaiseau, France; C. Cassou: European Center for Research and Advanced Training in Scientific Computation/Centre National de la Recherche Scientifique, Toulouse, France; Y. Fan: National Centers for Environmental Prediction, Camp Springs, Maryland, U.S.A.
Source: Geophysical Research Letters (GRL) paper 10.1029/2006GL028001, 2007
Materials provided by American Geophysical Union. Note: Content may be edited for style and length.
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