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Baroclinic Eddy Equilibration under Specified Seasonal Forcing

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Show simple item record Zhang, Yang Stone, Peter H. 2011-05-06T20:37:20Z 2011-05-06T20:37:20Z 2010-08 2009-11
dc.identifier.issn 0022-4928
dc.identifier.issn 1520-0469
dc.description.abstract Baroclinic eddy equilibration under a Northern Hemisphere–like seasonal forcing is studied using a modified multilayer quasigeostrophic channel model to investigate the widely used “quick baroclinic eddy equilibration” assumption and to understand to what extent baroclinic adjustment can be applied to interpret the midlatitude climate. Under a slowly varying seasonal forcing, the eddy and mean flow seasonal behavior is characterized by four clearly divided time intervals: an eddy inactive time interval in summer, a mainly dynamically determined eddy spinup time interval starting in midfall and lasting less than one month, and a quasi-equilibrium time interval for the zonal mean flow available potential energy from late fall to late spring, with a mainly external forcing determined spindown time interval for eddy activity from late winter to late spring. The baroclinic adjustment can be clearly observed from late fall to late spring. The sensitivity study of the eddy equilibration to the time scale of the external forcing indicates that the time scale separation between the baroclinic adjustment and the external forcing in midlatitudes is only visible for external forcing cycles one year and longer. In spite of the strong seasonality of the eddy activity, similar to the observations, a robust potential vorticity (PV) structure is still observed through all the seasons. However, it is found that baroclinic eddy is not the only candidate mechanism to maintain the robust PV structure. The role of the boundary layer thermal forcing and the moist convection in maintaining the lower-level PV structure is discussed. The adjustment and the vertical variation of the lower-level stratification play an important role in all of these mechanisms. en_US
dc.language.iso en_US
dc.publisher American Meteorological Society en_US
dc.relation.isversionof en_US
dc.rights Article is made available in accordance with the publisher's policy and may be subject to US copyright law. Please refer to the publisher's site for terms of use. en_US
dc.source American Meteorological Society en_US
dc.title Baroclinic Eddy Equilibration under Specified Seasonal Forcing en_US
dc.type Article en_US
dc.identifier.citation Zhang, Yang, Peter H. Stone, 2010: Baroclinic Eddy Equilibration under Specified Seasonal Forcing. J. Atmos. Sci., 67, 2632–2648. © 2010 American Meteorological Society. en_US
dc.contributor.department Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences en_US
dc.contributor.approver Stone, Peter H.
dc.contributor.mitauthor Stone, Peter H.
dc.relation.journal Journal of the Atmospheric Sciences en_US
dc.identifier.mitlicense PUBLISHER_POLICY en_US
dc.eprint.version Final published version en_US
dc.type.uri en_US
eprint.status en_US
dspace.orderedauthors Zhang, Yang; Stone, Peter H. en

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