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contributor authorde Vries, Hylke
contributor authorMethven, John
contributor authorFrame, Thomas H. A.
contributor authorHoskins, Brian J.
date accessioned2017-06-09T16:22:59Z
date available2017-06-09T16:22:59Z
date copyright2009/04/01
date issued2009
identifier issn0022-4928
identifier otherams-66865.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4208248
description abstractIn the Eady model, where the meridional potential vorticity (PV) gradient is zero, perturbation energy growth can be partitioned cleanly into three mechanisms: (i) shear instability, (ii) resonance, and (iii) the Orr mechanism. Shear instability involves two-way interaction between Rossby edge waves on the ground and lid, resonance occurs as interior PV anomalies excite the edge waves, and the Orr mechanism involves only interior PV anomalies. These mechanisms have distinct implications for the structural and temporal linear evolution of perturbations. Here, a new framework is developed in which the same mechanisms can be distinguished for growth on basic states with nonzero interior PV gradients. It is further shown that the evolution from quite general initial conditions can be accurately described (peak error in perturbation total energy typically less than 10%) by a reduced system that involves only three Rossby wave components. Two of these are counterpropagating Rossby waves?that is, generalizations of the Rossby edge waves when the interior PV gradient is nonzero?whereas the other component depends on the structure of the initial condition and its PV is advected passively with the shear flow. In the cases considered, the three-component model outperforms approximate solutions based on truncating a modal or singular vector basis.
publisherAmerican Meteorological Society
titleAn Interpretation of Baroclinic Initial Value Problems: Results for Simple Basic States with Nonzero Interior PV Gradients
typeJournal Paper
journal volume66
journal issue4
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/2008JAS2774.1
journal fristpage864
journal lastpage882
treeJournal of the Atmospheric Sciences:;2009:;Volume( 066 ):;issue: 004
contenttypeFulltext


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