关键词: 土壤水分, 质量控制, 质量评估, 自动站

Abstract: Soil moisture is one of soil components, it is important to the dissolution, transferring and absorbing of soil nutrition, in the meantime, it is the water source of vegetation and connected with vegetation physiological activity. China is an agricultural country; the application of soil moisture data is very significant for serving agriculture and disaster prevention and reduction. For these reasons, many hourly soil moisture Automatic Weather Stations (AWS) has been operated in China from 2010, in the present, the number of stations reaches more than 1 300. In order to assuring these data to be adequately used, the paper studies the quality control schemes for hourly soil moisture AWSs in China. Firstly, based on the ten days’ soil moisture from human observation data in 1981-2007 and hourly soil moisture from AWSs in 2010-2011, the paper analyzes the distributing characters of soil moisture four factors (including soil volumetric water content; soil gravimetric water content rates; soil relative humidity; available soil moisture) in each layer, founding that, the observation values and differences between each neighbor layers of soil moisture four factors are vertically divided into two parts, the dividing line of available soil moisture is 40 cm, and the other three factors is 50 cm. The observation values and differences between each neighbor layers are larger in the low parts, and it is very small in the deep parts; the hourly change of soil moisture is also vertically divided into two parts, the dividing line of four factors is all 40 cm, the hourly change is larger in the low layers (up 40 cm), mainly influenced by the precipitation or irrigation, and it is very stable in the deep layers (down 40 cm). Secondly, according to these characteristics and instrument measurement of soil moisture AWSs, the paper designs quality control schemes, including four checks, missing data check, climatic extreme value check, the vertical consistency check and the temporal consistency check, and develops the parameters for soil moisture four factors in each layer by statistics and human assessing. Finally, the quality control schemes are applied to hourly soil moisture AWSs in China, the quality assessment shows that, it is well usable to the quality control schemes, and it is well reasonable to the parameters of four factors. In the quality of soil moisture four factors, the missing rates keep around 8%, not changing along with the station number increasing; the usable rates all exceed 90% in each month between March 2010 and October 2011, and the average usable rates of four factors all exceed 97%, in otherwise, because of the inaccurate soil constant of soil moisture AWSs in the initial stages, the usable rate of available soil moisture is lowest between March 2010 and October 2010.

Key words: soil moisture, quality control, quality assessment, AWS