关键词: 土壤水分, 质量评估, 干旱监测

Abstract: The European Space Agency Climate Change Initiative soil moisture (ESA CCI_SM) product can provide soil volumetric water content data with high spatiotemporal coverage and a long time series. It can be used for drought monitoring on a regional scale. Gansu Province was selected as the study site for ESA CCI_SM testing. Soil volumetric water content data at the 0-10 cm depth from automatic station was used to evaluate the ESA CCI_SM product by analyzing the spatiotemporal variation characteristics of soil moisture in a long time series and construction of a soil moisture condition index (SMCI) for use in drought monitoring. The ESA CCI_SM product showed the best correlation (R=0.71) with observed values in the east of Gansu Province, followed by the middle, the south and Min county of Gansu Province. Overall, the 92% correlation coefficients of the sites were significant and passed 0.01 significant level. ESA CCI_SM indicated that it was more arid in the northwestern regions while it was more humid in the southeastern regions. Soil volumetric water content showed significant seasonal variation, which was relatively more humid in antumn, followed by summer, while in winter and spring it was drier. The SMCI constructed using the ESA CCI_SM product effectively exhibited the summer-autumn drought development from July to October 2002 and the spring-summer drought development from April to June 2009. This product had good drought monitoring capability in rain-fed agricultural areas in the middle and the east of Gansu Province.

Key words: microwave remote sensing, soil moisture, quality evaluation, drought monitoring