Study On Soil Moisture Simulated By CLM4.5 And Its Spatial And Temporal Variation In China

Soil moisture plays an important role in weather, climate, ecological system etc. While due to its high temporal and spatial variability, soil moisture in the long term and in a large extent is hardly to obtain. This makes it even vital to analyze the inter annual and inter decadal variability of soil moisture. In this paper, Comparison between simulations by CLM4.5 and station observations of soil moisture have been made to identify the temporal and spatial differences. Besides, Spatial variation pattern of soil moisture in China from 1951 to 2010 has been conducted to analyze its temporal and spatial characteristics. Moreover, the correlation between soil moisture and SPEI has been explored. The main conclusions are as follows:1.Simulations by CLM4.5 reveal the distribution of soil moisture characteristics, which is Northeast China is a semi humid zone, Yantze and Huaihe River Basin is the main wet center in China, while North China is a much dryier area, espeically in northwest regions as western Inner Mongolia and Xinjiang desert. Soil moisture in China gradually increases from northwest part to southeast region. In addition, Simulations are commonly higher than observations in China.2.Temporal and spatial variation and change cycle of soil moisture in China from 1951-2010 have been explored to specify the mutation time and range of soil moisture.Firstly, in terms of spatial field, sensitive area of climate anomalies on soil moisture is the Yangtze river basin. In North China there is significant soil moisture reduction. While in terms of time field, the first period of inter annual variation of soil moisture is 18 years, and the second period is 10 years. These two cycle take charge of the fluctuation of soil moisture in the whole time scale.From the point of regional analysis, soil moisture in Northeast China became wetter in the early 80s in 20th century, it decreased sharply in the middle of 90s. Soil moisture in North China dropped since the 90s in 20th century. Soil moisture changes quickly in the East and Central China, the oscillation phenomenon is obvious. Soil moisture in Southern China became wet in 1955 and got dry in 1960 and wet in 2002 respectively. Soil in Northwest China is very dry, while it tended to get wet since 2008.Based on simulations by CLM4.5 and SPEI product from 1951 to 2010 in China, SVD method is applied to explore the spatial and temporal variation between soil moisture and SPEI. Correlations of SVD first mode are 0.85,0.86,0.90,0.77 in four seasons respectively, showing that soil moisture and SPEI have significant temporal and spatial correlation characteristics.