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Please use this identifier to cite or link to this item:
http://hdl.handle.net/2031/5434
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| Title: | Structural asymmetries and track changes of tropical cyclones during landfall : Beta-plane simulations |
| Other Titles: | Re dai qi xuan deng lu shi zhi fei dui cheng jie gou ji lu jing bian hua : Beta ping mian mo ni
熱帶氣旋登陸時之非對稱結構及路徑變化 : Beta 平面模擬 |
| Authors: | Szeto, Koon Chuen (司徒冠銓) |
| Department: | Department of Physics and Materials Science |
| Degree: | Master of Philosophy |
| Issue Date: | 2008 |
| Publisher: | City University of Hong Kong |
| Subjects: | Cyclones -- Tropics. |
| Description: | CityU Call Number: QC942 .S94 2008
xviii, 98 leaves : ill. 30 cm.
Thesis (M.Phil.)--City University of Hong Kong, 2008.
Includes bibliographical references (leaves 91-94) |
| Type: | thesis |
| Abstract: | Numerical simulations are performed using the Weather Research and
Forecasting (WRF) Model to investigate the effects of coastline orientation,
land-surface moisture availability and friction on the motion and structure of a
tropical cyclone (TC) on a beta-plane during landfall. Experiments are carried
out by inserting a land surface with a north-south or west-east oriented coastline
at ~525 km west or north respectively from a spun-up TC undergoing a
northwestward beta drift. The results suggest that the pattern of secondary
circulation within TC is modified over most of the troposphere prior to landfall,
and such modification is most evident if the land surface friction is strong. Also,
when the land is rough, different modifications of the secondary flow are found
for different coastline orientations as a result of differential frictional
convergence/divergence along the coast induced by both the symmetric TC flow
and the asymmetric beta gyres. The southeasterly ventilation flow through the
TC center created by the beta gyres is thus modified as a result and the vertical
shear profile over the TC is also changed. For most of the rough-land cases,
differential vertical wind shear apparently plays an important role for the change
of convective structure of the TC during landfall. Together with the effect of
enhanced frictional convergence created by onshore wind and/or convective
instability due to three-dimensional advection of dry air when the surface is also
dry, a wavenumber-2 rainfall asymmetry could be established in some cases.
These changes in the flow and convective asymmetries modify the potential
vorticity tendency and thus affect the motion of the TC. |
| Online Catalog Link: | http://lib.cityu.edu.hk/record=b2340564 |
| URI: | http://hdl.handle.net/2031/5434 |
| Appears in Collections: | AP - Master of Philosophy
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