Large enhancements in southern hemisphere satellite-observed trace gases
due to the 2019/2020 Australian wildfires
Abstract
The 2019/2020 Australian wildfires emitted large quantities of
atmospheric pollutant gases and aerosols. Using state-of-the-art
near-real-time satellite measurements of tropospheric composition, we
present an analysis of several emitted trace gases and their long-range
transport, and compare to the previous (2018/2019) fire season.
Observations of carbon monoxide (CO) show that fire emissions were so
intense that the distinct Australian fire plume managed to
circumnavigate the Southern Hemisphere (SH) within a few weeks, with
eastward propagation over the South Pacific, South America, the South
Atlantic, Africa and the Indian Ocean. Elevated atmospheric methane
levels were also detected in January 2020 fire plumes over the Pacific,
defined using CO as a plume tracer, even though sampling was restricted
spatially by aerosols and clouds. Observations also show significant
enhancements of methanol from the fires, where CH3OH:CO enhancement
ratios increased within the aged plume downwind over the South Pacific
indicating secondary in-plume CH3OH formation.