Application of a satellite-based aridity index in dust source regions of northeast Asia

• A new satellite-based aridity index (SbAI) was introduced.
• The global distribution of SbAI was compared with standard aridity index.
• Threshold value of surface soil water content for dust emission was examined.
• Coverage of SbAI over 0.03 significantly affects Asian dust events over Japan.

A modified temperature-vegetation dryness index based on land-surface temperature was used to represent land-surface aridity in northeast Asia. Past results indicated that saltation activity and dust emission did not often occur in northeast Asia when soil water content was greater than 4% and normalized soil water content was greater than 0.2. The threshold value of the modified temperature-vegetation dryness index for dust emissions was assumed to be 0.8 when the normalized soil water content was 0.2. However, a detailed grid of meteorological data is needed to predict the modified temperature-vegetation dryness index; therefore, large-scale use is presently difficult. A new satellite-based aridity index using day/night land-surface temperature differences has been introduced and tested to represent the modified temperature-vegetation dryness index. The satellite-based aridity index was 0.03 when the modified temperature-vegetation dryness index was 0.8, which is the threshold for dust emissions. The relationship between coverage of satellite-based aridity index values greater than 0.03 in the target area (35°N–45°N and 100°E–115°E) and Asian dust events over Japan was analyzed for 2000–2011. Results indicated that coverage of satellite-based aridity-index values greater than 0.03 significantly affects Asian dust events over Japan (R2 = 0.4117, p < 0.05).