A Study On Characteristics Of Soil Moisture Calculated By Using Routine Weather Data In China Mainland

As one of the important variables in the land surface process, soil moisture play an important role in the climate through affecting the surface albedo, thermal capacity, latent heat, and sensible heat, etc, soil moisture is the most important factor for the climate change next to the sea surface temperature. In this paper, by using cloud cover, temperature, precipitation, relative humidity and wind speed data of506meteorological stations from1961to2010in China, daily evaporation and soil moisture were calculated, and the characteristics of temporal and spatial variation of water resource components and soil moisture were analyzed. The results are as follows:1. The spatial distribution of precipitation is decreased from the southeast to the northwest of China. The maximum precipitation is up to1600mm/a, but the minimum is less than100mm/a. Inter-annual variation trend of precipitation is increased in Gansu-Xinjiang area and South China, but decreased in the other areas. The biggest speed of decrease of precipitation is in Mongolia-Ningxia area and North China. The maximum evaporation capacity is in the northwest desert region and the minimum is in north of Northeast China,the next is Sichuan basin. Inter-annual variation of evaporation appears to increasing trend, and the most pronounced trend of which is Southern China, the next in Mongolia-Ningxia and Northeast China. The difference between precipitation and evaporation trend is increasing over China, and the decreasing trend of Mongolia-Ningxia area is the most significantly, next came the speed of Northeast China, only Gansu-Xinjiang area increasing trend.2. The maximum soil moisture is in the east of Tibetan Plateau, the next is south of Yangtze River and the north of Northeast China, and the minimum soil moisture is located in the desert region of Northwest China. A gradually increasing trend in Inter-annual changes in Gansu-Xinjiang area, the trend of other regions is reduced, and the biggest speed region of reducing is the Tibetan area, next came North China and South China. EOF analysis of summer soil moisture shows that the fist mode is the Jianghuai type soil humidity anomaly, indicating that the soil of Yangtze-Huaihe River Basin is the most sensitive. The time series reveals the drought of Yangtze-Huaihe River Basin in1994, the flood in1998and2003. The second mode is South China soil humidity anomaly. China can be divided into8zones by using REOF analysis, emphasizing on the sensitivity of the soil moisture of Yangtze-Huaihe River Basin to the climate change the same with EOF.3. The relationship between soil moisture and precipitation in the late is better than temperature in the late, and temperature responses more sensitive to the change of soil moisture, and lasts longer.4. Characteristic of atmospheric circulation and physical quantity field in abnormally wet and stem years of soil moisture was analyzed on.5. When summer soil moisture is anomalies dry, the West Pacific subtropical is weaker and eastward extension, along with weaker southwest monsoon in low level, convergence wind in high level, and weaker northward transport of water vapor, and divergence water vapor, higher surface temperature and temperature in low level; abnormally wet years is the opposite.