Characteristics Of The Climate Change In China In Last 50 Years

Using the surface observational data and upper air data (1951-2000) at 194 stations in China and the NCEP/NCAR reanalysis grid data (1951-2000), interannual variation and inter-decadal variation of climate in last 50 years is studied in this paper via various statistical analysis methods. Firstly, the change of East Asian Monsoon and the precipitation of East China is analyzed. Secondly, West China is divided into 5 parts, and then the variation of the temperature, surface temperature, precipitation, cloud amount and radiation of these areas are studied. Finally, the change trendency of temperature and humidity and the interrelationship between them are further discussed. The major conclusions are as follows:(1)In summer, the precipitation of Northeast China presents a decreased trend in latest 44 years, and it begins to increase in 1990s. The summer rainfall of North China drops and that of valley Yangtze-Huaihe River increases from 1947 to 2000. The precipitation in South China in summer has a change from increasing to decreasing. On the basis of the definition of East Asian Monsoon index by Qiao Yunting, it is found that the variation of the southwest monsoon, the southeast monsoon and the north monsoon are different. The intensity of southwest monsoon has been weakening until 1980s as well as the area's change. The southeast monsoon becomes weaker year after year; on the contrary, its range is enlarging. The north monsoon changes litter both in intensity and area in winter. It is demonstrated that the change of precipitation in East China has a close relation with the weakening of East Asian Summer Monsoon.(2)The climate characteristic of West China is studied and it is found that the annual average air temperature of these areas is rising in last 50 years and the change trend of surface temperature is same with air temperature, and particularly, the variation of surface temperature is more acutely. All the regions in West China show a rising trend in annual mean precipitation except Hetao area. The decreasing trends of annual mean total cloudiness and low cloudiness are observed in all the areas, with the most remarkable decreasing rate in Hetao area and the Southwest China. The change of solar direct radiation in the whole areas in West is similar with that of total radiation. The Southwest China experiences an increasing trend in solar diffuse radiation, while a dropping trend in the other four areas, and the most evidently decrease occurs in Xinjiang and Tibet. The cloud amount and aerosol consistency have a close connection with solar diffuse radiation. In Southwest China, the solar diffuse radiation decreases as the cloud amount increases, then we can guess the decreasing of solar diffuse radiation is caused by the increasing of aerosol consistency.(3)Both the annual average air temperature and seasonal average air temperature have a increasing trend in 9 areas in China, and the evaporation quantity has the similar trend with air temperature. The change of the absolute humidity in 850hPa is different in eastern part and western part of China. The annual average absolute humidity and seasonal average absolute humidity in East China, particularly in Southeast China, are getting less, but in West China, the change trend is on the contrary. It is maybe caused by the weakening of East Asian Summer Monsoon and increasing trend of air temperature in West China. The absolute humidity change differently in daytime and in nighttime and maybe it has relationship with the different change trend of air temperature in different time.