PyroCbs from Australia Fires and its Impact Study Using Satellite Observations from CrIS and TROPOMI and Reanalysis Data

Australia’s unprecedented fire disasters at the end of 2019 to early 2020 emitted huge amounts of carbon monoxide (CO) and fire aerosol particles to the atmosphere, particularly during the Pyrocumulonimbus (pyroCb) outbreak that occurred in southeast Australia between 29 December 2019 and 4 January 2020. It was estimated that at least 18 pyroCbs were generated during this episode, and some of them injected ice, smoke, and biomass burning gases above the local tropopause.  An unprecedented abundance of H₂O and CO in the stratosphere, and the displacement of background ozone (O₃) and N₂O from rapid ascent of air from the troposphere and lower stratosphere were found from satellite observations. Some other studies also found that the fire emissions and their long-range transport resulted in stratospheric aerosol, temperature, and O₃ anomalies after the 2020 Australian bushfires and altered the Antarctic ozone and vortex, posing great impact to local air qality and climate change.

            This study will focus on the thermodynamic state of atmosphere associated with these pyroCbs, and its impact on the change of the cloud properties and trace gases during this unprecedented Australia fires, mainly based on a new single Field of View (SFOV) Sounder Atmospheric Products (SiFSAP) and TROPOMI. SiFSAP was developed by NASA using the Cross-track Infrared Sounder (CrIS) and Advanced Technology Microwave Sounder (ATMS) onboard SNPP and JPSS-1, and will soon be available to the public at NASA DAAC. Since this product has a spatial resolution of 15 km at nadir, which is better than most global weather and climate models and other current operational sounding products, a process-oriented analysis of the dynamic transport of CO and fire plumes during this unprecedented fire disasters will be made in this study.  Based on a Principal Component Radiative Transfer Model (PCRTM) and an optimized estimation retrieval algorithm, a simultaneously retrieval is made using the whole spectral information measured by CrIS,  and the derived SiFSAP include temperature, water vapor, trace gases (such as O₃, CO₂, CO, CH₄ and N₂O), cloud properties and surface properties. Use of ATMS together with CrIS allows SiFSAP to get accurate retrieval products under thick pyroCb conditions. An algorithm to detect pyroCb based on the hyperspectral infrared sounder spectrum from CrIS will be developed and verified. In addition to SiFSAP sounding products,  CO, O₃, NO₂ from TROPOMI and O3 from OMPS will be used. The wind fields from the NASA’s Modern-Era Retrospective Analysis for Research and Applications Version-2 (MERRA-2) and ERA5 will be used to characterize the transport, and the SiFSAP temperature and water vapor profiles within and around pyroCbs will be compared with MERRA-2 and ERA5 products.