青藏高原东部定量降水数值预报试验及业务化应用评估
NUMERICAL SIMULATION OF PRECIPITATION IN THE EASTERN TIBETAN PLATEAU WITH LASG MESOSCALE MODEL AND ITS OPERATIONAL APPLICATION EVALUATION
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摘要: 该文运用LASG η坐标有限区域数值预报模式在青藏高原东部的川、渝两省市进行了定量、定点降水预报的数值模拟敏感性研究和准业务化试验, 并根据中国气象局的有关规定对结果进行了评估。经过对比分析发现:低纬度的天气系统与其活动特性, 对该地区定量、定点降水数值预报有着重要影响; 同样的物理过程和地形影响处理方式在不同的天气过程中对降水量的影响有显著差异; 可选用适当的客观分析方法, 通过强调距格点最近的站点的影响来尽量保持高、低值系统的极值, 从而改进预报效果。准业务化试验结果表明:LASG η坐标模式以其比较完善的动力框架和物理过程处理方法在这个地形复杂、天气系统多变的区域内可获得较好的预报结果, 特别是晴雨预报可获得较高的TS评分, 并能对某些客观预报难度较大的天气过程做出较好的预报。Abstract: The sensitive numerical simulating study and the quasi-operational experiment are made on heavy precipitation over the eastern Tibetan Plateau by means of the LASG η-coordinate area-limited mesoscale model with different schemes, and the results are evaluated according to the related regulations of the Chinese Meteorological Administration. The comparison and analysis indicate that the weather systems in the low latitudes with active features have important influence on the quantitative and fix-point precipitation prediction; in the same way, the effect of methods for processing physical processes and topographic influence on the precipitation prediction varies greatly with different weather processes. Through emphasizing the influence of the closest station to the grid point, the extremes of high and low-value systems are retained by using appropriate objective analysis methods, so to improve the forecasting performance. The quasi-operational experiments indicate that with the relatively perfect dynamic frame and the processing methods of physical processes, the LASG η-model performs well in such areas with a complicated topography and highly varied weather systems, especially in the clear-rainy forecast. Moreover, the model can be used to make reasonable forecast in some different cases.
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表 1 雨量等级划分
表 2 降雨个例时间表
表 3 目标区处于模拟区中不同位置时的评估结果
表 4 不同客观分析方案的TS得分
表 5 试验1、8、9对1998年8月1日个例的TS评分
表 6 不同地形高度模拟试验的TS得分
表 7 1998年7、8月准业务试验评估结果
表 8 1999年8月实时业务试验的TS评分
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