吉林省夏季(6-8月)低温多雨的中期天气分析及其预报

本文从统计低温多雨的冷空气路径、源地和移速入手,找出主要影响系统为贝加尔湖北部及雅库茨克的阻塞高压。并进一步运用候距平中心的移动规律,分析了这种结论的可靠性,指出在前1—2候就有正距平中心在该地区活动的先兆。 用谐波分析的方法,探讨了超长波的演变规律和阻塞高压的关系;提出阻塞高压的加强和稳定,主要是一波脊和三波脊在该地区重叠和持续的结果。在低温多雨前的7—14天,三波的振幅占绝对优势;高温少雨前的6—12天,一波振幅大于三波振幅。 最后,用逐日天气图上特定地区异常稳定的槽脊活动来表征,得出简单易行,确率达90％左右,预报时效较长的中期预报方法。

MEDIUM-RANGE WEATHER ANALYSIS AND FORECASTOF THE LOW TEMPERATURE IN WET SUMMER(JUNE-AUG.)

In this paper, by the statistical analysis of the path, source and moving velocity of the cold air, blocking high on the north of Baikal and Yakutsk was shown to be the main system of influence. We further analysed the reliability of the conclusion by the moving rule of the 500 mb five days mean anomaly centre, The centre of positive anomaly had been found active in the region before 5-10 days. We studied the relationship between the rule of transformation of ultra-long wave and blocking high by means of the barmonic analysis and the conclusions were as follows.