Satellite Evidence for Glyoxal Depletion in Elevated Fire Plumes

Space-borne observations are used to characterize the fate of formaldehyde and glyoxal in wildfire plumes. Their distribution measured by Tropospheric Monitoring Instrument reveals striking differences between two compounds near intense fires. In typical situations, glyoxal-to-formaldehyde ratio is highest fire (∼0.1) decreases downwind source area due larger contribution pyrogenic emissions abundance longer lifetime formaldehyde. However, a pronounced depletion detected above high-level clouds, not seen for formaldehyde, likely processing pyrocumulonimbus clouds generated This suggests retention upon droplet freezing and/or its outgassing hydrated form upper troposphere. The absence sizable loss during convection indicates that hydration liquid droplets subsequent as methanediol represent at most minor sink