午夜欧美大片免费观看,欧美激情综合五月色丁香,亚洲日本在线视频观看,午夜精品福利在线

Based on the Northern polar vortex index of the National Climate Center and the precipitation in Yunnan Province from 1961 to 2012, using the statistical analysis methods such as linear trend, composite analysis, and correlation analysis, the relationship between them is studied. The results show: (1) The polar vortex area (PVA), intensity (PVI) and position (St) index decreased during the period from 1961 to 2012； PVA and PVI in four seasons all had significant downward trends，while the trend of S(t) declined significantly only in summer. (2) A significant downward trend of precipitation at 124 stations in Yunnan Province was found; precipitation exhibited an increasing trend in spring and decreasing trends in the other seasons. (3) The correlation of the precipitation with PVA and in Yunnan Province was mainly characterized by negative value, and that with PVI was the opposite; in the early summer, PVA and PVI had significant effects on the later rainfall in Yunnan Province.