涡旋强度调整半径对2016年第18号热带气旋路径预报的影响

Impact of radius of TC intensity correction on No.1618 TC track prediction

  • 摘要: 2016年中国国家气象中心区域台风模式(GRAPES_TYM)对第18号热带气旋(记为TC 1618)的路径预报出现了较大的误差:其平均路径误差显著大于全年的平均误差。分析了涡旋初始化方案(包括涡旋重定位以及涡旋强度调整)对其路径预报的影响。结果显示,涡旋强度调整是造成TC1618预报路径平均误差偏大的主要原因。不同的强度调整半径(r0=12°,9°,6°,3°)对TC1618路径影响的敏感性试验结果显示,强度调整半径越大,其平均路径预报误差越大。500 hPa副热带高压以及平均海平面涡旋尺度分析发现:较大的强度调整半径(r0=12°,9°)其初始时刻的涡旋尺度较大,涡旋北侧邻近区域副热带高压等值线相对偏北,副热带高压相对偏弱。尺度大的涡旋其北移速度较大,并且在积分过程中其环流邻近区域副热带高压进一步减弱,导致涡旋环流会更早与其西北侧东移的西风槽结合,移速偏快。

     

    Abstract: The mean track error of the 18th tropical cyclone (TC) in 2016 (noted as TC 1618) predicted by the regional typhoon model GRAPES_TYM is much larger compared to that of all other TC forecasts in that year. The impact of vortex initialization scheme including vortex relocation and intensity correction is tested in this paper. The results show that vortex intensity correction is the main factor that causes the large mean track error. The sensitivity study of the impacts of different radii (r0=12°, 9°, 6°, 3°) of vortex intensity correction on the forecast track is further carried out. The results show that the larger the radius of intensity correction is, the bigger the mean track error would be. A larger intensity correction radius will produce a faster moving speed and larger moving direction error. Examinations of the subtropical high and the size of TC vortex in the mean sea level pressure field reveal that a larger intensity correction radius produces a larger TC vortex and a weaker subtropical high adjacent to the TC circulation in the initial time; the larger TC vortex moves northward faster, sustains the larger size of vortex and the weaker subtropical high to the north of the TC during integration. Eventually the larger vortex moves into the westerly trough earlier.

     

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