Wang, LS; Kotani, A; Tanaka, T; Ohta, T (2020). Assessment of drought condition using remotely sensed drought severity index and its correlations with soil moisture product in Inner Mongolia. THEORETICAL AND APPLIED CLIMATOLOGY, 141(2-Jan), 715-728.

Drought has a deep impact in Inner Mongolia, which relies on livestock and farming. The temporal and spatial variability of drought conditions in Inner Mongolia were analyzed with a drought severity index (DSI), which is derived from the ratio of evapotranspiration to potential evapotranspiration and the normalized difference vegetation index (NDVI), as measured by remote sensing. Soil moisture as an important drought measure has not been used in the calculation of DSI. Using monthly DSI data during the growing season (May-September) in 2001-2010, the relationship between DSI and soil moisture was investigated with correlation coefficient and regression analysis. Different seasonal and spatial patterns of drought occurrence were found in the notable drought years of 2001, 2007, and 2009. The largest correlations between DSI and soil moisture were attributed to the links between evapotranspiration and soil moisture. The spatial distribution of the correlation coefficients between DSI and soil moisture varied seasonally, tracking closely with the movement of rainfall belt. DSI could not reflect the variation of soil moisture in woodland. In grassland, DSI correlated with surface soil moisture in the east in the beginning of the growing season. As the rainfall belt expands to the west in the second half of the growing season, DSI reflected apparently deeper soil moisture conditions because of the spatial difference of soil properties, i.e., the water-holding capacity becomes larger from west to east.