阻塞高壓及其對台灣天氣之硏究

俞家忠

A study on the Blocking Highs and its associated weather over Taiwan

C. C. Yu

ABSTRACT

　　This paper is a study of the relationship between blocking highes and weather of Taiwan. By means of statistics, the first step is to find the numbers of occurence of blocking highes at 500 mb level in each cold month in the latest eleven years (1964-1974) in the pacific, Atlantic, Europe and Asia respectively, then the frequency of occurence along each longitude, the persistence, characteristics such as the occupied area of the blocking high, thermal structure, vertical development, the variation of intensity etc. Furthermore, to investigate how the weather of Taiwan was influenced by the blocking highes, and finally to find the method which can be used to predict the occurence and dissipation of the blocking highes.
　　This study shows some blocking highes did affect the weather of Taiwan to a great extent.
　　When a block high system in the vast land between Europe and Asia had moved to the east of 80 degree East, the weather of north Taiwan was always cloudy and rainy, unless the center of the particular blocking high was located to the north of 70 degree North, or there was another dominating high located at the southeast coast of China and Taiwan was affected by its thick, cold and dry northwest flow.
　　The blocking highes which extended to the west from the Pacific Ocean had even more influence to the weather of Taiwan. In most cases of this situation, Taiwan always had persisted bad weather, but if there was a low belt extended from the north pole, through the east of the Lake Baikal, up to the east of Japan, and a deep trough was located to the east of Taiwan, Taiwan could be affected by the cold and dry flow and had fine weather.
　　The occurence of the blocking highes in the Pacific can be predicted by realing that the negative(一) center of the 500 mb anomaly had moved to the seas south of Japan.