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A further study of the surface zonal flow predicted by an eddy flux parametrization scheme
Author(s) -
Wu G.X.,
White A. A.
Publication year - 1986
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49711247407
Subject(s) - parametrization (atmospheric modeling) , geostrophic wind , meridional flow , flow (mathematics) , zonal flow (plasma) , flux (metallurgy) , latitude , baroclinity , surface (topology) , mathematics , physics , mechanics , geology , geometry , geodesy , plasma , materials science , quantum mechanics , radiative transfer , metallurgy , tokamak
The problem of calculating the surface zonal flow using Green's large‐scale eddy flux parametrizations in spherical geometry is re‐examined. In a 2‐level, quasi‐geostrophic (QG1) model, low‐latitude easterlies and mid‐latitude westerlies of reasonable intensity can be obtained by assuming a more realistic baroclinicity than that applied in a study reported by White in 1977. This result also depends on the use of a more realistic value for the latitude average of a certain transfer coefficient; but no detailed treatment of its spatial variation is found to be necessary. Some further solutions are obtained using a strictly inconsistent formulation in which the Coriolis parameter is allowed its true latitude variation in all terms (in contrast to the QG1 model). In line with the conclusions of White's earlier study it seems in this case that detailed specification of the relevant transfer coefficient's spatial variation would be needed in order to produce a realistic surface zonal flow. Regarding the surface flow problem as a test of Green's parametrization scheme, we conclude that the latter performs quite well if QG1 approximations are applied to the Coriolis parameter. However, further refinement of the scheme is evidently required for good performance when these approximations are not applied.