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

An analysis is made of the climate variation trend and abrupt climate changes over the source region of the Yangtze River in the last 44 years based on the temperature and precipitation data of 5 stations and 500 hPa dew point data of 2 highaltitude stations. The result shows that the temperature increased over the region, and the variation range is greater in winter, but the tendency is obvious in summer; the annual and summery precipitation decreased, while increased in the other seasons; and the greater range is found in spring, more obvious tendency in winter. The annual average temperature shows a rising trend from the end of the 1960's to the early 1970's; the abrupt change from cold to warm happened in 1986; and the abrupt increasing of precipitation in winter and spring appeared in the 1970's and the 1980's. The signals that the climate becomes warm and humid in the source region of the Yangtze River climate appeared since 1986, and the main causes include the global climate warming, the resulting intensification of the evaporation over the oceans and lands, and the quicker surface water circulation and air moisture transportation.