On Typhoon Track Deflections near the East Coast of Taiwan

CCUR > College of Natural Science and Engineering > College of Science > Department of Atmospheric Sciences & Graduate Institute of Earth Science / Atmospheric Science > journal articles > Item 987654321/41884

Please use this identifier to cite or link to this item: https://irlib.pccu.edu.tw/handle/987654321/41884

Title:	On Typhoon Track Deflections near the East Coast of Taiwan
Authors:	Hsu, LH (Hsu, Li-Huan) Su, SH (Su, Shih-Hao) Fovell, RG (Fovell, Robert G.) Kuo, HC (Kuo, Hung-Chi)
Contributors:	大氣科學系
Keywords:	POTENTIAL VORTICITY TENDENCY CONDITIONALLY UNSTABLE FLOW BAROTROPIC VORTEX MOTION MESOSCALE MOUNTAIN-RANGE TROPICAL CYCLONE MOTION MOIST FROUDE-NUMBER IDEALIZED SIMULATIONS OROGRAPHIC INFLUENCE EXTREME RAINFALL TOPOGRAPHY
Date:	2018-05
Issue Date:	2019-01-17 15:31:38 (UTC+8)
Abstract:	Typhoons with "deflection tracks'' (DTs) within a 200-km distance of the mountainous island of Taiwan are examined. We analyze 84 landfalling typhoons that compose 49 DT cases turning to the left-hand side, including 18 with very large deflection angles (DA > 20 degrees) and another 7 having looped tracks (LTs). Most of the large DA and LT cases are "northern landfall'' type, reaching Taiwan's east coast poleward of 24 degrees N and originally possessing relatively slow translation speeds (similar to 4 ms(-1)). Their average translation speeds, however, increase by 50% in the 3 h prior to landfall. The WRF Model is used to simulate DT cases, and potential vorticity (PV) tendency diagnosis is used to interpret the contributions of the horizontal advection (HA), vertical advection (VA), and diabatic heating (DH) terms. The northern landfall tropical cyclones (TCs) possess significant cross-mountain flow to the south of the storm near the coast, resulting in vorticity stretching (the VA effect) and subsidence warming. The subsidence suppresses storm convection and produces heating asymmetries (the DH effect) that can induce significant southwestward deflections. The cross-mountain VA and DH effects are weaker for the "southern landfall'' storms. The results explain well the observed increase of translation speed prior to landfall in DT cases and show that the HA effect, in general, does not contribute to the track deflection. Our results highlight the impact of topography on TC track by the vorticity stretching effect and by asymmetric diabatic heating.
Appears in Collections:	[Department of Atmospheric Sciences & Graduate Institute of Earth Science / Atmospheric Science ] journal articles

Files in This Item:

File	Description	Size	Format
index.html		0Kb	HTML	175	View/Open

View Licence

Loading...