Tropopause-Level NO_x in the Asian Summer Monsoon

Deep convection within the Asian summer monsoon (ASM) transports surface level air into the upper troposphere-lower stratosphere (UTLS). This work aims to understand the distribution of NO₂, NO, and NO_x in the UTLS ASM anticyclone from satellite measurements. Observations of NO₂ from the Optical Spectrograph and InfraRed Imager System, the Atmospheric Chemistry Experiment - Fourier Transform Spectrometer (ACE-FTS), and the Stratospheric Aerosol and Gas Experiment III on the International Space Station are considered. The PRATMO photochemical box model is used to quantify the NO_x photochemistry, and to derive the NO_x concentration using OSIRIS NO₂ and O₃ observations. The satellite data show a relative minimum in NO₂ over the ASM in the summer months, while the corresponding NO and NO_x anomalies are elevated, mainly due to low O₃ and cold temperatures within the ASM. The observations within the ASM show reasonable agreement to simulations from the Whole Atmosphere Community Climate Model.