Application of Index Based on the Land Surface Temperature to Estimate the Threshold Wind Speed for Saltation Activity

Land-surface conditions, such as surface roughness and SWC (soil-water content), control the saltation activity and dust emission in northeast Asia. Information on spatial and temporal changes in surface SWC is needed for dust-modeling systems used to predict dust events with the aim of preventing the damage they cause. A MTVDI (modified temperature-vegetation dryness index) was tested to see if it could reproduce the surface SWC observed in Zhangye, China, and the Tottori Sand Dunes of Japan, and the threshold wind speed at the Tottori Sand Dunes. MTVDI was calculated from land-surface temperature using the MODIS (moderate resolution imaging spectroradiometer) product, and the aerodynamic minimum and maximum surface temperatures were estimated based on meteorological data. A greater correlation is seen between MTVDI and SWC than between SWC from AMSR-E (advanced microwave scanning radiometer-earth observing system) and SWC in Zhangye. The threshold wind speed for saltation activity decreased with increasing MTVDI, that is, with drying of the soil surface of the Tottori Sand Dunes. The correlation between MTVDI and threshold wind speed is statistically significant (R 2 = 0.2987).