Novel satellite and modelling studies to assess wildfire emission impacts on air quality and climate

Over recent years, we have become accustomed to hearing media stories around the world about large-scale wildfires destroying homes, ecosystems and degrading air quality (e.g. the 2019/2020 Australian wildfires; Pope et al., (2021)). With current and future climate and land-use change, it is expected that these wildfires will only become more intense and widespread.

These fires, as well as emitting smoke and ash, emit large quantities of air pollutants such as nitrogen oxides (NOx), carbon monoxide (CO) and aerosols. The aim of this project is to address the knowledge gap on the impact of wildfire emissions on primary and secondary air pollutants (e.g. tropospheric ozone (O3)) and reservoir species (key for transporting air pollutants to pristine regions) and their consequences for air quality and climate.

Aims and Objectives:

Satellite records of key trace gases, in combination with state-of-the-art chemistry-climate models, offer the exciting opportunity to study the impact of wildfire emissions on air quality and climate. Our project objectives are: 1) to assess the inter-annual variability of emissions and atmospheric composition over major wildfire regions; 2) to investigate the impact of wildfire emissions on secondary pollutants in downwind remote regions; and 3) to quantify the impact of wildfire emissions on climate (e.g. influence on radiative forcing).

Methodology:

A wealth of satellite measurements, using a range of remote sensing techniques and spectral information (e.g. UV, visible and IR wavelengths), enable us to monitor a suite of wildfire properties (e.g. burned area and fire radiative power) and key air pollutants (e.g. tropospheric columns or profiles). Here, we propose to use long-term NASA/ESA records of nitrogen dioxide (NO2) and formaldehyde (HCHO) from the Ozone Monitoring Instrument (OMI) and datasets generated by the UK National Centre for Earth Observation (NCEO) such as peroxyacetyl nitrate (PAN) from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) and CO (and a swath of hydrocarbons) from the Infrared Atmospheric Sounding Interferometer (IASI) and the Cross-track Infrared Sounder (CrIS).

The UK's Earth System Model (UKESM) couples together different model components of the Earth system (e.g. the atmosphere, oceans, land surface etc). A key novel component of UKESM is the INFERNO model (Teixeira et al., 2021) which simulates fire properties and pollutant emissions. Here, we will use the model and satellite data to explore the interaction of different pollutants and their secondary formation.

Targeted model sensitivity experiments can help determine the impact of wildfire emissions on air quality (e.g. long-range transport of reservoir species promoting a degradation of air quality in background regions), atmospheric chemical budgets and climate. Depending on the student's interest, we can also assess the model sensitivity to a more complex chemical scheme (Archer-Nicholls et al., 2021).

References: Archer-Nicholls et al., (2021), JAMES, doi: 10.1029/2020MS002420; Pope et al., (2021), JGR: Atmospheres, doi: 10.1029/2021JD034892; Teixeira et al., (2021), GMD, doi: 10.5194/gmd-2020-298.