The impact of different plume rise schemes on wildfire pollution dispersion and downwind PM2.5 exceedance prediction during 2020 and 2021 wildfire seasons
Abstract
Biomass burning releases a vast amount of aerosols into the atmosphere, often leading to severe air quality and exceedances of the health-based National Ambient Air Quality Standards (NAAQS) for fine particulate matter (PM2.5). The transport of the aloft smoke could affect air quality in the downwind region. The western United States experienced a record-breaking wildfire season in 2020, degrading air quality in 19 downwind states. In July 2021, the wildfire smoke from northwest Ontario, Canada reached the US East Coast. The smoke plume has touched down to the surface, causing a widespread air pollution episode. The simulation of the smoke injection height plays a vital role in downwind pollutant dispersion, as wind speed and direction generally change with height. To study the impact of different plume rise schemes on wildfire pollution dispersion and downwind PM2.5 exceedance, the GMU-CMAQ air quality system was conducted to simulate the Aug-Oct 2020 wildfire season and mid-July 2021 wildfire case, with three widely used plume rise schemes were tested, including Briggs 1969, Freitas 2007, and Sofiev 2012. For the 2020 wildfire season, western wildfires contributed 23% of surface PM2.5 in the contiguous US (CONUS), with a larger contribution in Pacific Coast (43%) and Mountain Region (42%). During the peak period, over 18% of surface area nationwide was blanketed in the unhealthy air caused by wildfire smoke. About half of the affected region was located in the Pacific Coast region, and the other half in the Mountain region. With a higher plume injection height, the surface PM2.5 concentrations were reduced more than 50% near the source, and increased ~ 10% in the downwind southwest region. For the 2021 mid-July case, surface PM2.5 exceedances were recorded in the US East Coast. With different plume schemes, the surface PM2.5 concentration differences reached 15% in the US East Coast.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMGH31A..03L