几率波在长期季度预报中的应用

本文首先讨论了造成长期异常天气的原因:主要是由于环流的持续稳定。指出月、季距平图上所反映的波动实质上是几率波动,它反映了下垫面冷热源(包括:雪盖、海冰、海温等)的异常分布。从而得出持续稳定的环流造成了下垫面冷热源的异常,而下垫面冷热源的异常分布作为一个持久性的扰动源对大气又起反馈作用,又造成了在某些特定地区环流的持续稳定,这样又形成了后期冷热源异常的再分布。 六个月距平几率波主要是反映下垫面冷热源的异常分布。它的变化是十分缓慢的。在30°N以南几乎呈静止状态,而30°N以北的几率波在欧亚大陆多数情况下是缓慢东进的。它的运动方向与下垫面的温度梯度相反。 最后利用半年时间尺度的距平几率波的特性,提出一种利用前一年秋到冬季的距平几率波预报次年春到夏季的降水、气温统计模型。经河北、内蒙、辽宁、吉林等省、区某些气象台1982—1985年的实地试用,反映较好,一致认为预报准确率比较稳定。

THE APPLICATION OF PROBABILITY WAVE IN LONG-RANGE SEASONAL PREDICATION

First, it is discussed that the anomaly in long-range weather is due to sustained stable circulation. Waves in monthly or seasonal departure maps can be regarded essentially as probability waves which reflect the anomaly distribution of cold and heat sources on earth surface. The persistent stable circulation creates these distributions which serve as persistent disturbance sources and in turn feedback the general circulation with persistent stability in later period. The departure probability waves in six-month (Sept,-Feb.) charts reflect the abnormal distribution of cold and heat sources on earth's surface which move slowly in north of 30°N and eastward on Eurasian continent in opposition to temperature gradient. But the waves are stationary in south of 30°N. The characteristics of the six-month departure probability waves are used to develop a statistical model to predicate spring-summer temperature and precipitation of next year. It has been tested in several North China provinces for four years with encouraging results.