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contributor authorLin, Yuh-Lang
contributor authorChen, Shu-Hua
contributor authorLiu, Liping
date accessioned2017-06-09T16:59:08Z
date available2017-06-09T16:59:08Z
date copyright2016/10/01
date issued2016
identifier issn0022-4928
identifier otherams-77453.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4220013
description abstractseries of idealized numerical experiments and vorticity budget analyses is performed to examine several mechanisms proposed in previous studies to help understand the orographic influence on track deflection over a mesoscale mountain range. When an idealized tropical cyclone (TC) is embedded in a uniform, easterly flow and passes over a mountain with a moderate Froude number, it is deflected to the south upstream, moves over the mountain anticyclonically, and then resumes its westward movement. The vorticity budget analysis indicates that the TC movement can be predicted by the maximum vorticity tendency (VT). The orographic effects on the above TC track deflection are explained by the following: 1) Upstream of the mountain, the easterly basic flow is decelerated as a result of orographic blocking that causes the flow to become subgeostrophic, which advects the TC to the southwest, analogous to the advection of a point vortex embedded in a flow. The VT is primarily dominated by the horizontal vorticity advection. 2) The TC passes over the mountain anticyclonically, mainly steered by the orographically generated high pressure. This makes the TC move southwestward (northwestward) over the upslope (lee slope). The VT is mainly contributed by the horizontal vorticity advection with additional contributions from vorticity stretching and the residual term (which includes friction and subgrid turbulence mixing). 3) Over the lee slope and downstream of the mountain, the northwestward movement is enhanced by asymmetric diabatic heating, making the turning more abrupt. 4) Far downstream of the mountain, the VT is mainly contributed by the horizontal vorticity advection.
publisherAmerican Meteorological Society
titleOrographic Influence on Basic Flow and Cyclone Circulation and Their Impacts on Track Deflection of an Idealized Tropical Cyclone
typeJournal Paper
journal volume73
journal issue10
journal titleJournal of the Atmospheric Sciences
identifier doi10.1175/JAS-D-15-0252.1
journal fristpage3951
journal lastpage3974
treeJournal of the Atmospheric Sciences:;2016:;Volume( 073 ):;issue: 010
contenttypeFulltext


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