Eddies and the Annular Modes of Climate Variability

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Read Full Article Cited by GEOPHYSICAL RESEARCH LETTERS, VOL. 26, NO. 20, PAGES 3133–3136, 1999 Eddies and the Annular Modes of Climate Variability Varavut Limpasuvan Department of Atmospheric Sciences, University of Washington, Seattle, Washington Dennis L. Hartmann Department of Atmospheric Sciences, University of Washington, Seattle, Washington Abstract The dominant modes of month-to-month variation in the troposphere are realistically simulated in a general circulation model whose lower boundary is prescribed with realistic topography and seasonally varying, climatological sea surface temperatures. In both hemispheres, these internal modes describe a nearly zonally symmetric, North-South shifting of the zonal jets as anomalous westerlies vacillate between high (50°-60°) and low (30°-40°) latitudes. The eddy structures evolve with the jets, and the corresponding eddy momentum forcings support the shifts in jet position. Stationary (synoptic) wave variations mainly account for the total eddy forcings in the Northern (Southern) Hemisphere. Pronounced eddy variations occur over the North Atlantic sector. Received 23 March 1999; accepted 28 June 1999. Read Full Article Cited by Citation: Limpasuvan, V., and D. L. Hartmann (1999), Eddies and the Annular Modes of Climate Variability, Geophys. Res. Lett., 26(20), 3133–3136. Copyright 1999 by the American Geophysical Union.