Precipitation Forecast of MM5 in the Taiwan Area during the 1998 Mei-yu Season
Precipitation Forecast of MM5 in the Taiwan Area during the 1998 Mei-yu Season
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1998年梅雨季台湾地区MM5降水量预报
DOI：
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
Ming
中科院分区：
文献类型：
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作者：
F. Chien;Y. Kuo;Ming
本研究利用美国宾夕法尼亚州立大学-国家大气研究中心的第五代中尺度模式（MM 5），于1998年梅雨期对台湾地区的降水进行了实时验证。最高的公平威胁分数（ETS）的降水预测，验证对观测到的降水量，约为0.2在2.5毫米的阈值，这近2个月的时间。该地区复杂陡峭的地形对15公里模型预测实际降雨量提出了巨大挑战，因为降水是由热效应和地形抬升等局部强迫作用驱动的。此外，由于缺乏对周围海洋的观测数据，极大地限制了模型初始数据的质量。结果发现，该模型系统更准确地模拟夜间降雨比白天降水。这是由于模型低估了白天太阳能加热和山坡地形抬升造成的降雨事件。然而，在高山地区（0.1200米）的降水量被高估了。此外，ETS的地形高度方面的分析表明，该模型表现更好的低地比山区（斜坡和高地）。结果表明，东亚夏季风爆发后，东亚夏季风爆发前的ETSs值明显高于爆发后的ETSs值。总体而言，该模型更准确地预测降水的梅雨锋和伴随的中尺度对流系统的降雨事件比它预测降水与当地强迫。
This study presents precipitation verification, in the Taiwan area, for a real-time Pennsylvania State University‐ National Center for Atmospheric Research Fifth-Generation Mesoscale Model (MM5) system during the 1998 Mei-yu season. The highest equitable threat score (ETS) of precipitation forecasts, verified against observed precipitation, was about 0.2 at the 2.5-mm threshold for this nearly 2-month period. The complex and steep terrain in this region presented great challenges to the 15-km model in predicting realistic rainfall because the precipitation was driven by local forcings such as thermal effects and orographic lifting. In addition, the lack of observational data over the surrounding ocean greatly limited the quality of the model’s initial data. It was found that the model system more accurately simulated nighttime rainfall than daytime precipitation. This was caused by the model underforecasting the rainfall events that resulted from solar heating and orographic lifting over the mountain slopes during the daytime hours. Precipitation, however, was overforecast over the high mountain regions (.1200 m). Further, the analysis of ETS with regard to the terrain height indicated that the model performed better over the lowlands than over the mountainous areas (slopes and highlands). It was discovered that the ETSs were much higher for precipitation forecasts after the onset of the east Asia summer monsoon than prior to the onset. Overall, the model more accurately predicted precipitation for the rainfall events associated with the Mei-yu front and the accompanying mesoscale convective systems than it predicted precipitation associated with the local forcings.