| Popis: |
Smoke from wildfires are a significant source of air pollution, which can adversely impact ecosystems and the air quality in downwind populated areas. With increasing severity of wildfires over the years, these are a significant threat to air quality in densely populated areas. Emissions from wildfires are most commonly estimated by a bottom-up approach, using proxies such fuel type, burn area, and emission factors. Emissions are also commonly derived with a top-down approach, using satellite observed Fire Radiative Power. Furthermore, wildfire emissions can also be estimated directly from satellite-borne measurements.Here, we present advancements and improvements of direct emission estimates of forest fire NOx emissions by using TROPOMI (Tropospheric Monitoring Instrument) high-resolution satellite datasets, including NO2 vertical column densities (VCDs) and information on plume height and aerosol scattering. The effect of smoke aerosols on the sensitivity of TROPOMI to NO2 (via air mass factors) is estimated with recalculated VCDs, and validated with aircraft observations. Different top-down emission estimation methods are tested on synthetic data to determine the accuracy, and the sensitivity to parameters, such as wind fields, satellite sampling, instrument noise, NO2:NOx conversion ratio, species atmosphere lifetime and plume spread. Lastly, the top-down, bottom-up and direct emission estimates of fire emissions are quantitatively compared. |
