A51N-0268
COMPOSITION AND ORIGIN OF THE ASIAN TROPOPAUSE AEROSOL LAYER (ATAL)
Friday, 18 December 2015
Poster Hall (Moscone South)
Thomas Duncan Fairlie1, Jean-Paul Vernier2, Murali Natarajan1, Tobias Wegner1, A. Jayaraman3, M Venkat Ratnam4, Harish S Gadhavi4, Amit Kumar Pandit4, Noel C Baker1, Terry Deshler5, Georgiy L Stenchikov6 and Larry Willis Thomason7, (1)NASA Langley Research Center, Hampton, VA, United States, (2)Science Systems and Applications, Inc. Hampton, Hampton, VA, United States, (3)National Atmospheric Research Laboratory, Gadanki, India, (4)National Atmospheric Research Laboratory, Department of Space, Gadanki, India, (5)University of Wyoming, Laramie, WY, United States, (6)King Abdullah University of Science and Technology, Thuwal, Saudi Arabia, (7)NASA Langley Research Ctr, Hampton, VA, United States
Abstract:
Satellite observations from SAGE II and CALIPSO indicate that summertime aerosol extinction has doubled in the Asian Tropopause Aerosol Layer (ATAL) since the late 1990s. We show in-situ measurements from balloon-borne platforms to validate the CALIPSO backscatter observations, and use in-situ data from aircraft and a chemical transport model (GEOS-Chem), to explore the likely composition, and origin, of the ATAL. The aircraft data indicate significant sulfate and carbonaceous contributions to the ATAL, which is supported by the CTM results. We use back trajectory calculations initialized from CALIPSO observations to provide evidence that deep convection over North India is a significant source for ATAL through the vertical transport of pollution to the upper troposphere. Source elimination studies using GEOS-Chem indicate that 80-90% of the aerosol in the ATAL originated from Asian sources, in contrast with much lower (~30%) estimates in earlier studies. Results are sensitive to parameterized wet scavenging in the model.
