Effects of asymmetric latent heating on typhoon movement crossing taiwan: The case of morakot (2009) with extreme rainfall

Chung Chieh Wang, Hung Chi Kuo, Yu Han Chen, Hsiao Ling Huang, Chao Hsuan Chung, Kazuhisa Tsuboki

    研究成果: 雜誌貢獻期刊論文同行評審

    55 引文 斯高帕斯(Scopus)

    摘要

    Typhoon Morakot struck Taiwan during 6-9 August 2009, and it produced the highest rainfall (approaching 3000 mm) and caused the worst damage in the past 50 yr. Typhoon-monsoon flow interactions with mesoscale convection, the water vapor supply by the monsoon flow, and the slow moving speed of the storm are the main reasons for the record-breaking precipitation. Analysis of the typhoon track reveals that the steering flow, although indeed slow, still exceeded the typhoon moving speed by approximately 5 km h21 (1 km h215 0.28 m s21) during the postlandfall period on 8 August, when the rainfall was the heaviest. The Cloud- Resolving Storm Simulator (CReSS) is used to study the dynamics of the slow storm motion toward the northnorthwest upon leaving Taiwan. The control simulations with 3-km grid size compare favorably with the observations, including the track, slow speed, asymmetric precipitation pattern, mesoscale convection, and rainfall distribution over Taiwan. Sensitivity tests with reduced moisture content reveal that not only did the model rainfall decrease but also the typhoon translation speed increased. Specifically, the simulations consistently show a discernible impact on storm motion by as much as 50%, as the storms with full moisture move slower (;5 km h21), while those with limited moisture (#25%) move faster (;10 km h21). Thus, in addition to a weak steering flow, the prolonged asymmetric precipitation in Typhoon Morakot also contributed to its very slow motion upon leaving Taiwan, and both lengthened the heavy-rainfall period and increased the total rainfall amount. The implications of a realistic representation of cloud microphysics from the standpoint of tropical cyclone track forecasts are also briefly discussed.

    原文英語
    頁(從 - 到)3172-3196
    頁數25
    期刊Journal of the Atmospheric Sciences
    69
    發行號11
    DOIs
    出版狀態已發佈 - 2012 十一月

    ASJC Scopus subject areas

    • Atmospheric Science

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