New Inventory of Dust Emission Sources in Central Asia and Northwestern China Derived From MODIS Imagery Using Dust Enhancement Technique

The first inventory of dust emission sources in Central Asia and northwestern China (35-50 degrees N, 50-100 degrees E) derived from the twice daily MODIS imagery from 2003 to 2012 is presented. A high-resolution (1 km) dust enhancement product was generated to produce maps of dust point sources (DPS), indicating geographical locations of the observed dust emissions, and gridded data sets of dust emission frequencies. About 13,500 DPS were detected over an area of similar to 5 x 10(6) km(2), however, their distribution was uneven. The highest frequency of DPS occurred in the northern and eastern Taklimakan, in the Aralkum, and in the regions, which were not widely reported in literature before, the Balkh delta in northern Afghanistan and the pre-Aral, from the northern Caspian coast to the Betpak-Dala desert in Kazakhstan. South of the Aral, DPS were mainly associated with fluvial features: drying lakes, dry river beds, alluvial deposits and agricultural activity which is closely linked to water availability in this arid region. In the pre-Aral and Balkhash-Junggar regions, land damaged by wildfire was the main source of dust. In China and eastern Kazakhstan dust emissions peaked in spring; in Central Asia and western Kazakhstan-in summer. The Aralkum was active throughout the year with a positive trend in emission frequency over the study period. Locations of DPS did not always correlate with high atmospheric optical depth (AOD) particularly west of the Aral and in the southern Taklimakan where few DPS were detected despite the high AOD values. This was attributed to dust transport from the upwind sources.

Automated summary

This study presented the first inventory of dust emission sources in Central Asia and northwestern China based on MODIS imagery data from 2003 to 2012. It found that dust point sources were unevenly distributed, with the highest frequency occurring in specific regions like the Taklimakan desert and the Aralkum. Dust emissions peaked in different seasons in different regions, such as in spring in China and eastern Kazakhstan, and in summer in Central Asia and western Kazakhstan.