[Analysis of Spatio-temporal Distribution and Variation Characteristics of Aerosol Optical Depth over the Northwest of China by MODIS C6 Product]

This work compared the collection 6 MODIS aerosol optical depth products with sun photometer data from AERONET, and evaluated the applicability of C6 merged data in the northwest of China. The spatio-temporal variation characteristics and influencing factors of AOD over northwest of China were analyzed by MODIS/AQUA C6 MYD08-M3 products from 2006 to 2015, and the results showed that Southern Xinjiang and Guanzhong region of Shanxi province had relatively high AOD, whereas the south of Qinghai and Gansu province had low values; Junggar Basin was the incremental area of AOD for the first 5 years and second 5 years, whereas converse result existed in Qaidam Basin and Hetao area. Temporally, the yearly mean AOD ranged from 0.18 to 0.22, and the declined trend occurred in 2011, and the annual decrease rate was about 0.32%; Because of different intensity and frequency of dust weather, the south of Xinjiang showed a significant interannual variation characteristic; East of the northwest displayed an obviously declining trend from 2011 to 2015, and the yearly mean decrease was about 1.1%. The AOD in north of Xinjiang and Qinghai-Tibet remained stable. The seasonal changes of AOD among different areas over the northwest had the same trend, all gradually declined from spring to autumn, and increased in winter.