台风异常北上时期的天气和次天气尺度环境场特征
The Characteristics of Synoptic and Subsynoptic Scale Environmental Field in the Period of Typhoon Unusual Northward Movement
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摘要: 本文利用一个空间滤波器、将台风环境场分解为天气和次天气尺度。在此基础上,对两个异常北上的台风路径(8211号台风(Cecil)和8305号台风(Abby))进行诊断分析。结果表明:台风异常北上时期出现在天气尺度环境场发生环流调查过程中,在500 hPa高度场上,台风异常北上时,表现出向着次天气尺度扰动中心传播方向移动的趋势,在天气尺度环境场作用明显减弱时期,这可能是导致台风路径异常的重要因素;同时,在动能场上,台风则表现出向着正值的次天气尺度动能制造区伸展方向移动。Abstract: A spatial filter is used to separate the typhoon environmental flow into a synoptic and a subsynopticscale components. Two unusual typhoon paths (Cecil (1982) and Abby (1983)) traviling towards are diagnosted. The results show that the anomalous path occurs in the period of synopticscale circulation adjustment from 500 hPa height field. This kind of typhoons has a tendency moving along the propagation direction of subsynoptic scale disturbance center when the typhoon travels unusually northwards. This is an interesting process, which may be responsible for the unusual typhoon path when the synoptic scale circulation is evidently weak. In light of kinetic energy field, typhoon movement is in accordance with the extending direction of the positive area of GKE (the generation of subsynoptic scale kinetic energy) during this period
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