Identification

Title

The influence of an SST front on a heavy rainfall event over coastal Taiwan during TiMREX

Abstract

A long-lived heavy precipitation area was observed along the southwest coast of Taiwan from 13 to 18 June 2008 during the Terrain-Influenced Monsoon Rainfall Experiment (TiMREX). Rainfall amounts exceeded 500 mm along portions of the coast, and the coastal plains experienced severe flooding. The precipitation systems were influenced by blocking effects, as the southerly moist monsoon flow impinged on the island. A relatively strong gradient in the sea surface temperature (SST) off the southwest coast of Taiwan existed during the rainfall event. Mesoscale SST fronts are known to influence the planetary boundary layer (PBL) such that low-level convergence and precipitation are enhanced under certain circumstances. In this study, the authors investigate the role of the SST front in enhancing the 13-18 June 2008 precipitation event over Taiwan using the Weather Research and Forecasting (WRF) Model. In control simulations with the observed SST, there is a transition from a well-mixed to a stable PBL across the front, causing the low-level flow to decelerate, resulting in an enhancement of horizontal convergence. Such a transition in the PBL and the associated convergence is greatly reduced in smoothed SST gradient model simulations, which produce over 20% less precipitation over southwest Taiwan. Sensitivity tests show that, qualitatively, the results are independent of the existence of the island of Taiwan. These findings indicate that the SST gradient over the northern South China Sea during the early summer monsoon can have a significant impact on the intensity of rainfall over Taiwan.

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document

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http://n2t.net/ark:/85065/d7kk9cr3

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Dataset language

eng

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geoscientificInformation

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title

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reference date

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publication

effective date

2016-01-01T00:00:00Z

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publication

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2014-09-01T00:00:00Z

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Copyright 2014 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be "fair use" under Section 107 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Law (17 USC, as revised by P.L. 94-553) does not require the Society's permission. Republication, systematic reproduction, posting in electronic form on servers, or other uses of this material, except as exempted by the above statements, requires written permission or license from the AMS. Additional details are provided in the AMS Copyright Policies, available from the AMS at 617-227-2425 or amspubs@ametsoc.org. Permission to place a copy of this work on this server has been provided by the AMS. The AMS does not guarantee that the copy provided here is an accurate copy of the published work.

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OpenSky Support

organisation name

UCAR/NCAR - Library

full postal address

PO Box 3000

Boulder

80307-3000

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opensky@ucar.edu

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http://opensky.ucar.edu/

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pointOfContact

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