Pyrocumulonimbus Stratospheric Plume Injections Measured by the ACE-FTS

The Atmospheric Chemistry Experiment (ACE) is a satellite-based mission that probes Earth's atmosphere via solar occultation. The primary instrument on board is a high-resolution infrared Fourier transform spectrometer (Atmospheric Chemistry Experiment Fourier Transform Spectrometer, ACE-FTS), providing altitude-resolved volume mixing ratio measurements for numerous atmospheric constituents, including many biomass burning products. The ACE mission has observed the aftermath of three major pyrocumulonimbus events, in which extreme heat from intense fires created a pathway for directly injecting into the stratosphere plumes of gaseous and aerosol pollutants. These three events were associated with severe Australian bushfires from 2009 and 2019/2020, along with intense North American wildfires from summer 2017. The ACE-FTS measured stratospheric plumes containing aerosols, enhanced levels of gaseous fire products, and tropospheric air transported into the stratosphere. Infrared spectral features indicate strikingly similar aerosol composition for all three events, characteristic of oxygenated organic matter. Plain Language Summary The Atmospheric Chemistry Experiment (ACE) is a satellite-based mission for studying the Earth's atmosphere. During the 16+ years of operation for the mission, three extreme fire events were observed that injected gases and smoke particles very high into the atmosphere (near 20 km in altitude). The amount of gas and the nature of the smoke particles were studied, in an effort to provide insight into the effect of such fires on climate and atmospheric chemistry.