THE VARIATION OF WIND FIELD ALONE 140°E DURING THE LAST STAGE OF MAI-YÜ

Based on wind data at 200 mb over Tateno, Japan, for June-august, 1950-1956. We discussed the variation of wind field during the last stage of Mai-yü in eastern Asia. It is found that the northward displacement of westerly Jet stream and the appearrance of easterly wind is a good index of the end of Mai-yii period and the beginning of prevailing summer season.Besides, the 5-days mean cross sections of zonal wind along 140°E for the period of June and July, 1954-1956 are constructed. From them we further found that during the last stage of Mai-yü, with the northward retreat of the upper westerlies over Japan, the subtropical ridge apparantly shifts northward and the typhoons which were limited to the south western part of the Paciffic now begin to invade East sea and Yellow sea one by one. These facts are probably helpful to predication.