Large-scale circulation classification, weather regimes, and local climate over France, the Alps and Western Europe

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 17:303-324 (2001) - doi:10.3354/cr017303 Large-scale circulation classification, weather regimes, and local climate over France, the Alps and Western Europe Guy Plaut1,*, Eric Simonnet2 1Institut Non Linéaire de Nice CNRS, Université de Nice - Sophia Antipolis, 1361 route des Lucioles, 06560 Valbonne, France 2Laboratoire de Météorologie dynamique du CNRS, Ecole Polytechnique, 91128 Palaiseau, France *E-mail: plaut@inln.cnrs.fr ABSTRACT: By applying the dynamical cluster algorithm to large-scale circulation patterns at various tropospheric levels (Z700, Z500, and SLP sea-level pressure), we obtain the so-called weather regimes (WRs). WRs are the cluster central patterns; there is no subjectivity at all involved in the procedure. A red noise test allows one to select the best number of clusters at each level. A comparison is performed between the different level classifications, and highly significant correlations are found. While previous attempts to classify daily circulations in a fully objective way were concerned with mid-tropospheric levels and could not go further back than 50 yr, here we classify 120 yr of SLP patterns. We arrive at the important conclusion that the same 5 WRs are found for the 3 periods 1880-1918, 1919-1957 and 1958-1997. The linkage between these WRs and the local tangible weather is then investigated for both temperatures and precipitation. It is found that the instantaneous departure of local weather from average climate is highly correlated with the WRs, making this approach a challenging and coherent description of local climates. The atmosphere does not merely evolve around its mean state, but instead spends more time around a few peculiar (large-scale) states with specific consequences for local weather. As a result, the WRs may provide a reliable (and moreover fully objective) framework for building downscaling algorithms appropriate for local climate change studies. KEY WORDS: Classification · Large-scale circulation · Weather regime · Local climate · European Alps · France Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in CR Vol. 17, No. 3. Online publication date: August 29, 2001 Print ISSN: 0936-577X; Online ISSN: 1616-1572 Copyright © 2001 Inter-Research.