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contributor authorMeng, Zhiyong
contributor authorZhang, Yunji
date accessioned2017-06-09T17:29:04Z
date available2017-06-09T17:29:04Z
date copyright2012/02/01
date issued2011
identifier issn0027-0644
identifier otherams-86091.pdf
identifier urihttp://onlinelibrary.yabesh.ir/handle/yetl/4229610
description abstractased on a 3-yr (2007?09) mosaic of radar reflectivity and conventional surface and synoptic radiosonde observations, the general features of squall lines preceding landfalling tropical cyclones (TCs) (pre-TC) in China are examined and compared with their midlatitude and subtropical counterparts. The results show that about 40% of landfalling TCs are associated with pre-TC squall lines with high-occurring frequency in August and from late afternoon to midnight. Most pre-TC squall lines form in a broken-line mode with a trailing-stratiform organization. On average, they occur about 600 km from the TC center in the front-right quadrant with a maximum length of 220 km, a maximum radar reflectivity of 57?62 dBZ, a life span of 4 h, and a moving speed of 12.5 m s?1. Pre-TC squall lines are generally shorter in lifetime and length than typical midlatitude squall lines.Pre-TC squall lines tend to form in the transition area between the parent TC and subtropical high in a moist environment and with a weaker cold pool than their midlatitude counterparts. The environmental 0?3-km vertical shear is around 10 m s?1 and generally normal to the orientation of the squall lines. This weak shear makes pre-TC squall lines in a suboptimal condition according to the Rottuno?Klemp?Weisman (RKW) theory. Convection is likely initiated by low-level mesoscale frontogenesis, convergence, and/or confluence instead of synoptic-scale forcing. The parent TC may contribute to (i) the development of convection by enhancing conditional instability and low-level moisture supply, and (ii) the linear organization of discrete convection through the interaction between the TC and the neighboring environmental system.
publisherAmerican Meteorological Society
titleOn the Squall Lines Preceding Landfalling Tropical Cyclones in China
typeJournal Paper
journal volume140
journal issue2
journal titleMonthly Weather Review
identifier doi10.1175/MWR-D-10-05080.1
journal fristpage445
journal lastpage470
treeMonthly Weather Review:;2011:;volume( 140 ):;issue: 002
contenttypeFulltext


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