Ammonium nitrate and biomass burning pollution in the UTLS: First results from GLORIA airborne measurements of Asian Monsoon outflow during the PHILEAS campaign 2023

We present trace gas and aerosol measurements obtained by the airborne infrared imaging limb sounder GLORIA (Gimballed Limb Observer for Radiance Imaging of the Atmosphere) that has been operated onboard HALO (High Altitude and Long Range Research Aircraft) during the PHILEAS campaign (Probing High Latitude Export of air from the Asian Summer Monsoon ; August-September 2023). We measured outflow from the Asian Monsoon above the North Pacific, and the Mediterranean, as well as pollution plumes from biomass burning events in North America. In this contribution, we present retrieval results of ammonia (NH3), solid ammonium nitrate and other pollution trace gases (e.g. PAN) as two-dimensional distributions with high vertical resolution, derived from GLORIA observations in the UTLS (Upper Troposphere Lower Stratosphere). Our GLORIA observations reveal considerable abundances of solid ammonium nitrate, which is connected to the Asian Monsoon, in the lower stratosphere outside the Asian Monsoon Anticyclone. Measurements from a previous airborne campaign within the Asian Monsoon (StratoClim 2017) showed large enhancements of NH3 (precursor of ammonium nitrate), and solid ammonium nitrate in the Asian Monsoon upper troposphere. Further, GLORIA measured UTLS air masses heavily influenced by biomass burning during PHILEAS. Due to the ability of GLORIA to measure pollution trace gases with different atmospheric life times, we are able to estimate the age of individual plumes, based on their chemical composition. As an example, we show measurements from a PHILEAS flight, influenced by aged and fresh pollution. In a first analysis, we compare our measurements with atmospheric models to examine air mass origins. In particular, we use artificial tracers calculated by the ICON-ART (ICOsahedral Nonhydrostatic - Aerosol and Reactive Trace gases), one of the models that was also used in forecast configuration for flight planning.