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contributor authorScinocca, John F.
contributor authorSutherland, Bruce R.
date accessioned2017-06-09T16:34:18Z
date available2017-06-09T16:34:18Z
date copyright2010/08/01
date issued2010
identifier issn0022-4928
identifier otherams-70195.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4211949
description abstractA new effect related to the evaluation of momentum deposition in conventional parameterizations of orographic gravity wave drag (GWD) is considered. The effect takes the form of an adjustment to the basic-state wind about which steady-state wave solutions are constructed. The adjustment is conservative and follows from wave?mean flow theory associated with wave transience at the leading edge of the wave train, which sets up the steady solution assumed in such parameterizations. This has been referred to as ?self-acceleration? and it is shown to induce a systematic lowering of the elevation of momentum deposition, which depends quadratically on the amplitude of the wave. An expression for the leading-order impact of self-acceleration is derived in terms of a reduction of the critical inverse Froude number Fc, which determines the onset of wave breaking for upwardly propagating waves in orographic GWD schemes. In such schemes Fc is a central tuning parameter and typical values are generally smaller than anticipated from conventional wave theory. Here it is suggested that self-acceleration may provide some of the explanation for why such small values of Fc are required. The impact of Fc on present-day climate is illustrated by simulations of the Canadian Middle Atmosphere Model.
publisherAmerican Meteorological Society
titleSelf-Acceleration in the Parameterization of Orographic Gravity Wave Drag
typeJournal Paper
journal volume67
journal issue8
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/2010JAS3358.1
journal fristpage2537
journal lastpage2546
treeJournal of the Atmospheric Sciences:;2010:;Volume( 067 ):;issue: 008
contenttypeFulltext


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