THE INTERDECADAL VARIATION OF SUMMER PRECIPITATIONS IN CHINA AND THE DROUGHT TREND IN NORTH CHINA
HUANG Rong hui XU Yu hong ZHOU Lian tong (Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100080)
The interdecadal variations of summer precipitation in China and the drought trend in North China are analysed by using the observed data of summer precipitations (June～August) at 336 stations in China and SST in the Pacific from 1951 to 1994. The analysed results show that a climate jump of summer precipitation in China occurred in 1965. Since 1965, the summer precipitations in North China have obviously decreased and drought trend is obvious there. This drought trend is analogous to that in the Sahel area of West Africa. The analysed results also show that the climate in China in the 1980's was obvious different from that in the 1970's. This difference is that the precipitation in the Yangtze River-the Huai River valley increased and flood disasters obviously increased from the later 1970's, while the precipitations in South and North China in the period from the 1980's to the early 1990's were obvious less than those in the 1970's and drought trend was more and more severe there. However, from the middle 1990's, there was an increasing trend in the precipitation in the northern part of North China. The above mentioned climatic change may be due to the obvious temperature warmings in the middle 1960's and the period from the 1980's to the early 1990's and the obvious cooling in the 1970's in the equatorial eastern and central Pacific, respectively, This phenomenon is like an interdecadal “ENSO Cycle”phenomenon, and it may has a larger impact on the global climatic change and the climatic change in China, especially on the drought trend in North China. However, there is a cooling trend in the SST of the tropical eastern and central Pacific from the middle 1990's, and this is helpful to the increase of precipitation in North China.