Stochastic Models of Quasigeostrophic Turbulence |
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| Authors: | Timothy Delsole |
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| Institution: | (1) George Mason University, Fairfax, VA, 22030-4444, U.S.A.;(2) Center for Ocean-Land-Atmosphere Studies, Calverton, MD, 20705-3106, U.S.A. |
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| Abstract: | Atmospheric and oceanic eddies are believed to be manifestations of quasigeostrophic turbulence — turbulence that occurs in
rapidly rotating, vertically stratified fluid systems. The heat, momentum, and water transport by these eddies constitute
a significant component of the climate balance, without which climate change cannot be understood. A major, unsolved problem
is whether the turbulent eddy fluxes can be parameterized in terms of the large-scale, background flow. In the past, stochastic
models have been used quite extensively to investigate quasigeostrophic turbulence in the case in which the eddy statistics
are isotropic and homogeneous. Unfortunately, these models ignore the background shear which is absolutely essential to maintaining
the eddies in the presence of dissipation. Recent attempts to extend stochastic models to shear flows have shown significant
skill in predicting the structure of the eddy fluxes in arbitrary, three-dimensionally varying flows. This paper provides
an accessible introduction to these models. The topics reviewed include quasigeostrophic turbulence and two-dimensional turbulence,
non-modal andoptimal perturbations, mathematical theory of stochastic models, stochastic model simulations with realistic
background states, and recent closure theories. A list of unsolved problems concludes this review. |
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| Keywords: | nonnormal quasigeostrophic singular vedors stochastic turbulence |
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