Transport Pathways and Sources Associated with the Asian Tropopause Aerosol Layer during 2006-2011

Recent studies have shown a wide spread aerosol layer in the tropopause layer over Asia during boreal summer, referred to as the “Asian Tropopause Aerosol Layer” (ATAL). This aerosol layer extends from Eastern Mediterranean (down to North Africa) to Western China (down to Thailand), and vertically from 13 to 18 km. By using Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) aerosol profile data and NOAA Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model, we found three major pathways: The first pathway starts from the Middle East, passes through Central Asia to West China, and then turns to South Asia. The second one starts from eastern Afghanistan, reaches East China and then turns southward. The third one directly starts from East Asia and moves southwestward. Three major potential source regions are identified: (1) Middle East; (2) Central Asia; (3) East China. The relative contributions of each pathway and source region are also analyzed and will be discussed.