谱松弛同化技术对台风路径及强度模拟的影响-海洋预报

谱松弛同化技术对台风路径及强度模拟的影响

单位：1. 国家海洋环境预报中心, 北京 100081;
2. 国家海洋局海洋灾害预报技术研究重点试验室, 北京 100081

分类号：P444

出版年·卷·期（页码）：2018·35·第三期（17-29）

摘要：

采用WRF模式针对2016年第17号台风"鲇鱼"设计了多组对比试验及敏感性试验，考察谱松弛同化技术对台风路径及强度模拟的影响。通过其与格点松弛方法的对比发现：这两种方法都能显著改善台风路径和强度的模拟，由于谱松弛方法仅部分同化高层的大尺度场，允许模式更好的发展自身的中小尺度信息，其模拟的台风强度较格点松弛试验模拟的台风强度更接近观测。对影响谱松弛方法的关键参数松弛波数及系数进行的敏感性试验表明：台风模拟对谱松弛波数及系数的选择均很敏感。适当增加波数可以改善台风路径及强度的模拟，但并非波数越多越好，波数超过一定阈值会导致模拟的台风强度明显偏弱；适当增大系数同样能改善台风路径和强度的模拟，但并非越大越好，需根据模式设置优化选取。本研究表明：选取谱松弛波数为5，系数为0.000 3~0.003时，台风模拟有显著改进。

Multiple group contrast tests and sensitivity tests for the 17th Typhoon"Megi"in 2016 are designed using the WRF model to study the influence of spectral nudging assimilation technique on typhoon track and intensity simulation. By contrasting the influence of spectral nudging with grid nudging on Typhoon simulation, it turns out that:both of the two methods can significantly improve the simulation of track and intensity of typhoon. Spectral nudging method only partially assimilate large scale field of high-level, permitting model to develop better small scale information on its own, though the simulated typhoon intensity of spectral nudging is closer to observation than of grid nudging. The results from sensitivity tests of spectral nudging parameters, nudging wave number and coefficient showing that Typhoon simulation is sensitive to wave number and coefficient. Proper increase of wave number can improve the simulation of typhoon track and intensity, but not the larger the better. The wave number over a certain threshold will cause the typhoon intensity to be weaker. Appropriately increasing the coefficient can also improve typhoon simulation, but not the larger the better. It is necessary to choose the best according to the mode setting. This study shows that selecting spectral nudging wave number as 5, and the coefficient as 0.0003~0.003, improves the typhoon simulation greatly.

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