Space-time analysis of geopotential height and SLP, intraseasonal oscillations, weather regimes, and local climates over the North Atlantic and Europe

Abstract

CR Climate Research Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsSpecials CR 17:325-342 (2001) - doi:10.3354/cr017325 Space-time analysis of geopotential height and SLP, intraseasonal oscillations, weather regimes, and local climates over the North Atlantic and Europe Eric Simonnet1,*, Guy Plaut2 1Laboratoire de Météorologie dynamique du CNRS, Ecole Polytechnique, 91128 Palaiseau, France 2Institut Non-Linéaire de Nice CNRS, Université de Nice-Sophia Antipolis, 1361 route de Lucioles, 06560 Valbonne, France *E-mail: esimon@lmd.ens.fr ABSTRACT: We extract coherent and robust oscillations at the intraseasonal time scale using multichannel singular spectrum analysis (MSSA). Three daily fields are compared, namely sea-level pressure (SLP) and geopotential heights at 500 and 700 hPa (Z500 and Z700). The data set extends from 1958 to 1997 and covers the same North Atlantic-European domain. Three oscillations stand out with periods of 30-35, 65-70 and 120-130 d respectively. A comparison shows that the same period oscillations at different levels are highly correlated. Moreover, it is shown that these modes are phase-locked and thus should come out from a single limit cycle. When these oscillations are compared with the succession of weather regimes (WRs), it can be shown that WR occurrences are indeed strongly influenced by particular phases of the 30-35 and 65-70 d modes. Transition from one WR to another is also shown to be favored by the life cycle of the previous modes. For instance, zonal regimes are followed preferably by blocking ones. Thus, regime transitions are indeed not random but are somehow steered by the dynamical behavior of a low-dimensional atmospheric attractor. We then explore the links between the intraseasonal modes and the local temperatures over France and Western Europe as well as precipitations over France. Once again, we conclude that bursts of low-frequency oscillations, such as the ones detected, significantly influence local surface weather conditions. KEY WORDS: Multichannel singular spectrum analysis (MSSA) · Intraseasonal oscillations · Sea-level pressure (SLP) · Geopotential height · Weather regimes Full text in pdf format PreviousExport 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.