Seasonal variation of dust plumes and their impact on global AOD

Dust is a significant type of aerosol that contributes to the aerosol effect and is one of the leading uncertainties in global climate studies today [IPCC, 2001 and 2007]. Locally produced aerosols and their impact on local climates have been studied for decades by numerous researchers for decades, however studying the transcontinental and transpacific transport of both dust and aerosols is relatively new (Husar et al. 2001, Logan et al. 2010) because these transports play a vital role in the understanding of regional and global climate change. To what extent do these seasonal dust plumes impact the regional/global aerosol loading is one of the unsolved issues. In this study, Moderate Resolution Imaging Spectoradiometer (MODIS) aerosol products retrieved by using PSF-weighted method are used to study the AOD over Asian dust source region, as well as its downwind regions (Pacific ocean and North America). Preliminary results have shown that AOD values are much higher over East Asia (100-120 longitude), then monotonically decrease over Pacific Ocean (120-230 longitude), and finally slightly increase over West coast of North America (230-250 longitude). AOD values increase from February to March, reach the max around April, and then decrease from May to June. The slight increase AOD over West coast of North America is highly possible due to local contribution, not from Asian dust storms. By analyzing the global AOD distribution, the preliminary results show very strong seasonal variations of AOD over the desert regions, such as Gobi desert. The most pronounced variations occurred during the spring seasons over Asian continent, indicating that the AOD variations can be linked to the strong dust storms. In this study, the impact of such strong seasonal variations of aerosol loading to global aerosol optical depth has been also investigated.