Development of a new dust index NDLI for Asian dust extraction system based on Aqua MODIS data and monitoring of trans-boundary Asian dust events in Japan

Heavy Asian dust events occur due to the strong wind in the Gobi deserts and are occasionally carried to Korea, Japan, and North America. They cause problems in human lives, such as respiratory diseases, transportation disturbances due to reduce visibility, and other disruptions in social activities. Remote sensing technology is useful for detecting and monitoring such airborne dust and understanding the distributions and movements of dust. To understand the Asian dust events, in this study, a new dust index is developed for the efficient detection of airborne Asian dust, which is a composite of two Moderate Resolution Imaging Spectroradiometer (MODIS) indices: Brightness Temperature Difference (BTD) and Normalized Difference Dust Index (NDDI). Our proposed Normalized Dust Layer Index (NDLI) detects dust more efficiently. To identify the characteristics of annual Asian dust events in Japan, a statistical time-series analysis of data from the years 2010, 2013 and 2014 is performed, and it is found that the dust events in 2014 were relatively calmer than those in 2013. An evaluation that was based on ground observations over different sites in Japan indicated that the proposed method performed well. Finally, we integrated our NDLI product into the trans-boundary air pollution satellite image database (TAPSIDB) system for monitoring Asian dust events.