Analysis of Atmospheric Energy Transport in ERA40 and Implications for Simple Models of the Mean Tropical Circulation

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Analysis of Atmospheric Energy Transport in ERA40 and Implications for Simple Models of the Mean Tropical Circulation

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dc.contributor.author Kuang, Zhiming
dc.contributor.author Peters, Matthew
dc.contributor.author Walker, Christopher
dc.date.accessioned 2009-08-05T15:59:09Z
dc.date.issued 2008
dc.identifier.citation Peters, Matthew E., Kuang, Zhiming M., and Christopher C. Walker. 2008. Analysis of atmospheric energy transport in ERA40 and implications for simple models of the mean tropical circulation. Journal of Climate 21(20): 5229-5241. en
dc.identifier.issn 0894-8755 en
dc.identifier.uri http://nrs.harvard.edu/urn-3:HUL.InstRepos:3203689
dc.description.abstract An analysis of atmospheric energy transport in 22 years (1980-2001) of the 40-yr ECMWF Re-Analysis (ERA-40) is presented. In the analyzed budgets, there is a large cancellation between divergences of dry static and latent energy such that the total energy divergence is positive over all tropical oceanic regions except for the east Pacific cold tongue, consistent with previous studies. The west Pacific and Indian Oceans are characterized by a balance between diabatic sources and mean advective energy export, with a small eddy contribution. However, in the central and eastern Pacific convergence zone, total energy convergence by the mean circulation is balanced by submonthly eddies, with a small diabatic source. Decomposing the mean advective tendency into terms due to horizontal and vertical advection shows that the spatial variation in the mean advection is due largely to variations in vertical advection; these variations are further attributed to variations in the vertical profile of the vertical velocity. The eddy energy export, due almost exclusively to eddy moisture export, does not exhibit any significant seasonal variation. The relationship between the eddies and the mean circulation is examined. Large-scale moisture diffusion is correlated with eddy moisture export on (500 km)(2) spatial scales, implying that eddy activity preferentially dries narrow convergence zones over wide ones. Eddy moisture export is further linked to the depth of mean convection in large-scale convergence zones with larger eddy export associated with shallower circulations. This suggests a mechanism that could contribute to the observed variation in mean divergence profiles across the northern tropical Pacific whereby sea surface temperature gradients set the width of convergence zones and eddy activity modulates the tropospheric relative humidity and divergence profile. The importance of variations in the vertical profile of the vertical velocity and eddies in closing the energy budget implies that simple models of the mean tropical circulation should include these effects. en
dc.description.sponsorship Earth and Planetary Sciences en
dc.language.iso en_US en
dc.publisher American Meterological Society en
dc.relation.isversionof http://dx.doi.org/10.1175/2008JCLI2073.1 en
dc.relation.hasversion http://www.people.fas.harvard.edu/~kuang/itcz_mse_budget.pdf en
dash.license OAP
dc.title Analysis of Atmospheric Energy Transport in ERA40 and Implications for Simple Models of the Mean Tropical Circulation en
dc.relation.journal Journal of Climate en
dash.depositing.author Kuang, Zhiming

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  • FAS Scholarly Articles [6929]
    Peer reviewed scholarly articles from the Faculty of Arts and Sciences of Harvard University

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