Evaluating the UTLS nitrate model during the Asian summer monsoon season

The Asian Summer Monsoon (ASM) effectively transports pollutants from boundary layers to the upper troposphere and lower stratosphere (UTLS) and forms the Asian Tropopause Aerosol Layer (ATAL). Weve developed a sectional UTLS aerosol model containing all primary ATAL aerosols such as sulfate, primary organics, secondary organics (SOA), ammonia, and nitrate. We evaluate the model during the 2017 ASM season and compare the simulations with available satellite and in-situ data. We find the SOA and ammonium nitrate contribute significantly to the UTLS extinction between 0-45N in Asia. Condensed nitrate appears both inside and outside the ASM anticyclone in East Asia and the West Pacific Ocean. We are investigating the sources of the nitrate.