Spatial-Temporal Variations of Temperature and Precipitation in Northern China in Recent 50 Years

The spatial-temporal variations of temperature and precipitation in Northwestern China during the period of 1959-2008 were studied,using the observed surface air temperature and precipitation data at 180 stations from 1959 to 2008 and the climate trend coefficient and climate tendency ratio.The results show that:(1) The temperature of the region has markedly ascended in the last 50 years,the warming rate of 0.32 ℃·(10 a)-1 is significantly higher than rest of China and global average rate of warming at the same period.The warming rate of 0.37 ℃·(10 a)-1 in winter is significantly higher than other seasons.(2) In details,the mean temperature ascended in the early of 1960s,but dropped in late of 1960s,whereas it ascended in 1980s again and ascended sharply in 1990s.(3) The variability of precipitation is regionally different.There is significantly increasing trend of precipitation in western and middlle of northwestern China,however declining trend in eastern of northwestern China.(4) The monthly trend of precipitation is different to seasonal precipitation and annual precipitation regionally,however in spring,summer and fall the trends of precipitation are accordant to trend of annual precipitation.