Evaluating the Atmospheric Impact of the Australian 2019/2020 Wildfire Season

Smoke from the extreme 2019/2020 Australian wildfire season had wide-scale atmospheric impacts regionally within the southeast of the continent, as well as further afield over New Zealand and South America due to transported pollution at low and lofted altitudes. We use a combination of chemistry-climate modeling and remote sensing to investigate the impact of the wildfire emissions on atmospheric chemistry. The Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICA) is used with regional refinement capability (at ~14 km spatial resolution) applied over Australia, and 1 degree resolution (~100 km) elsewhere, within the NSF NCAR Community Earth System Model (CESM). MUSICA allows for simultaneous simulation at human and policy-relevant scales at the same time as climate, hemispheric and global-scales. Results are shown with several model updates, including smoke plume rise, diurnal cycle in emissions and implementation of a new dust scheme. We compare the regional refined results with global simulations at 1 degree to evaluate the representation of model processes at finer spatial scales. We also compare against satellite measurements such as the Measurements Of Pollution In The Troposphere (MOPITT) observations of carbon monoxide, a good tracer for wildfire smoke, as well as the Moderate Resolution Imaging Spectroradiometer (MODIS) aerosol optical depth (AOD), to evaluate model performance.