Wildfires can be important drivers of poor air quality. Numerical atmosphere models are routinely used to estimate pollutant concentrations emitted from a wide range of sources, including from wildfires. Such models often take the Eulerian field or Lagrangian particle method for representing mass and transport in the atmosphere. Using the Saddleworth Moor and Winter Hill fires that occurred in North West England in 2018 as a case study, we compared these two methods consistently within the same model framework. We also explored the impact of model spatial resolution on predicted concentrations and health impacts. In the Eulerian simulations, as the horizontal resolution was made finer (from 12 km to 1 km) the horizontal spread of the downwind wildfire pollution decreased substantially, leading a smaller geographical area and population being impacted by the smoke. The estimated number of people exposed to poor air quality due to wildfire from the 1 km Eulerian simulation was 30% lower than from the 12 km Eulerian simulation. A health impact assessment found a similar relative decrease for the estimated excess mortality due to short-term PM2.5 exposure when going from 12 km to 1 km horizontal resolution. Estimated air quality impacts were also found to be sensitive to horizontal resolution for the Lagrangian simulations but to a lesser degree (∼10% decrease from 12 km to 1 km). We recommend that model spatial resolution should be considered as a source of uncertainty for wildfire air quality impact assessments, particularly when an Eulerian model is used.
CORE (COnnecting REpositories)
CORE (COnnecting REpositories)