Model-derived prevalence of forest fire smoke at Aerosol Limb Imager (ALI, on HAWCsat) measurement altitudes

Wildfires are becoming more common in Canada. Particulate matter from these fires is transported over long distances, affecting meteorology and air quality at locations far removed from the sites of the fires. Monitoring and forecasting the transport of PM2.5, a severe hazard to human health, is of increasing importance.

The Aerosol Limb Imager (ALI) on the upcoming Canadian satellite mission HAWC (High-altitude Aerosols, Water vapour and Clouds) will detect aerosols in the atmosphere. It is anticipated that ALI will contribute to monitoring the transport of forest fire smoke.

Pre-launch, we use data from the Environment and Climate Change Canada (ECCC) Regional Air Quality Deterministic Prediction System (RAQDPS) model to determine how often forest fire smoke, at concentrations exceeding specific thresholds, is likely to occur at altitudes which ALI can measure: 5-35 km above mean sea level. Threshold concentrations tested are: (1) PM2.5 concentrations from forest fires alone (other sources subtracted) which exceed ALI's minimum detectable level; (2) total PM2.5 concentration from all sources combined which exceed the Health Canada acceptable limit for air quality and which include a contribution from forest fires.

Data from the 2023 summer forecast season was selected because RAQDPS was run twice for that time period: one run including, and the other run excluding, inputs from the Canadian Forest Service (CFS) Forest Fire Emissions Prediction System (CFFEPS). Therefore, PM2.5 concentrations related specifically to forest fires can be isolated.

Measurements from the MPLCAN network of miniMicroPulse Lidars provide context and comparison measurements for the model data.