Monitoring Wildfires through Satellite Views of their Carbon Monoxide Emissions

This project aims to investigate the following research questions: 1) How have global and regional atmospheric CO concentrations, and the sources and sinks of CO, varied in recent years?

2) How can we exploit our understanding of CO sources to better understand the drivers of biomass burning in different ecosystems? 3) What does this imply about the future of wildfires under anthropogenic climate change? 4) How is the global carbon cycle currently affected by biomass burning? Methods

This project uses novel satellite data, state-of-the-art atmospheric models and statistical estimation methods. Launched in 2017, the TROPOMI instrument onboard European Space Agency's (ESA) Sentinel-5P satellite, provides high resolution CO-monitoring capability with excellent sensitivity near the surface. These data have not yet been comprehensively exploited to quantify CO emissions from fires and other sources.

Additionally, the research will employ the TOMCAT chemical transport model, which has been extensively used to simulate the complex atmospheric transport and chemical processes for numerous species including CO (e.g. Pope et al., 2021). TOMCAT will allow assessment and comparison of the current best estimates of CO emissions from all sources to TROPOMI and other observations.

This work will additionally make use of TOMCAT's inverse modelling framework (Wilson et al., 2014). Data assimilation methods optimise surface sources so that the model representation of atmospheric CO best matches observations. This provides extra constraint of the fire-related emissions estimates in line with what was observed in reality.

A new 'nested' high-resolution grid module will allow for detailed regional analysis of fire emissions and focus on how tropical regions (e.g. central Africa, Southeast Asia) respond to the significant global El Niño event that is likely during the 2023/24 fire season.

Linking CO fire emissions to overall carbon loss through emission ratios for different ecosystem types will allow for investigation of the overall global carbon budget, with data assimilation of multiple atmospheric species such as methane (CH4) and carbon dioxide (CO2) improving our understanding of the biosphere's carbon balance.