Analyses on variety characteristics of temperature in Yellow River and Yazang sources in recent 40 years

This paper is mainly studied temperature change on Yellow River and Yazang sources and analyzed the features of the daily minimum temperature as well as the daily maximum temperature and the daily minimum temperature in Yellow River and Yazang sources in 1961-2001.This paper has achieved some conclusions: the daily mean temperature ,the daily maximum temperature and the daily minimum temperature all increased in recent 40 years in this area. The increasing speed of daily minimum temperature is faster than that of the daily maximum temperature. The temperature in 1990s is apparently higher than that in the former period and the main new feature in 1990s is that the January daily maximum temperature, daily minimum temperature and daily mean temperature do not get warmer but colder. There is abrupt changes in the daily mean temperature ,the daily maximum temperature, the daily minimum temperature in 1980s.