利用MJO活动规律进行云南雨季开始期的延伸期预测试验
Extended-Range Forecast of the Beginning of the Rainy Season in Yunnan by Studying the MJO Action Regularity
中文摘要：
雨季开始期的早晚历来是云南天气气候预测中的一个重要课题，特别是在近年来云南春季和初夏极端干旱事件频频发生的情况下，以及在社会和政府决策需提前预知雨季来临早迟的“刚性”需求下，对“雨季开始期”的延伸期预测显得极为迫切。为此，在应用MJO活动规律开展云南冬半年延伸期降水预测试验的基础上，结合前期对“热带低频振荡与云南雨季关系”的研究成果开展了本次“云南雨季开始期延伸期预测试验”，并进行了认真的检验。通过检验，认为：（1）在预测中可根据MJO活动中心位置对应的影响云南水汽输送的干、湿窗口期，较好地预测延伸期时段内云南的降水趋势；（2）前期研究发现了影响云南多雨年、少雨年的对流活动关键区，此关键区春季前兆信号指数对云南雨季开始期的预测是有效的。因此，综合应用MJO移动规律和关键区前兆信号开展云南雨季开始期的预测是提高预测能力的一种有效途径。
中文关键词：
MJO，云南，雨季开始期，延伸期预测，试验
KeyWords：
MJO, Yunnan, the beginning of the rainy season, extended-range forecast, experiment
Abstract：
When the rainy season begins is always a significant issue in Yunnan's forecast of weather and climate. The extendedrange forecast for the beginning date of rainy season is urgent and necessary, especially in the case of extreme droughts in Spring and early Summer in Yunnan occurring frequently for the past few years. Thus, based on doing extended-range forecast of precipitation through the winter half-year in Yunnan using the patterns of MJO activity, and combined with early research findings about the relationship of the tropical low-frequency to the rainy season in Yunnan, the extended-range forecast for the beginning date of the rainy season has been fully studied and examined. The results suggest the points below: (1) The precipitation trends can be forecasted by the wet and dry windows phase that would impact water vapor transportation of Yunnan which corresponds to the position of the action center of MJO. (2) In our previous research we found some key areas which had exercised an influence on the convection of the wet or dry years in Yunnan. The index of spring’s precursory signal in the key areas is effective to forecast the beginning of the rainy season. Thus, using both MJO moving regularity and precursory signal in the key areas is an effective way to improve prediction of the beginning date of the rainy season.