Natural and Anthropogenic Aerosols in the UTLS: Sources and the Role of Monsoon Transport

We present our study of decadal variations of UTLS aerosols in terms of the origins and transport mechanisms through modeling and analysis of observations. We use the global model GOCART, which incorporates emissions from anthropogenic, biomass burning, volcanic, and other natural sources including dust and sea salt, to simulate the aerosols and track their origins. The model results are compared to Aura and other satellite observations from OMI, MLS, CALIOP, OSIRIS, and Envisat instruments as well as aircraft observations from CARIBIC. Although volcanic sources exerts large, sporadical perturbation to the UTLS aerosol composition, mainly due to the nature of volcanic eruptions and relatively high altitude injections, anthropogenic aerosols, not only from Asia but also from other regions, are transported from surface to high altitudes mainly via the monsoonal convective transport with well-organized seasonal cycles in the UT region. We estimate the relative contributions of natural and anthropogenic aerosols in different altitudes in UTLS and discuss the implication of the continuous increase of Asian anthropogenic emissions.