Satellite‐derived aerosol radiative forcing from the 2004 British Columbia wildfires

Abstract

The British Columbia wildfires of 2004 was one of the largest wildfire events in the last ten years in Canada. Both the shortwave and longwave smoke aerosol radiative forcing at the top‐of‐atmosphere (TOA) are investigated using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth's Radiant Energy System (CERES) instruments. Relationships between the radiative forcing fluxes (?F) and wildfire aerosol optical thickness (AOT) at 0.55 μm (τ0.55) are deduced for both noontime instantaneous forcing and diurnally averaged forcing. The noontime averaged instantaneous shortwave and longwave smoke aerosol radiative forcing at the TOA are 45.8±27.5 W m−2 and ‐12.6±6.9 W m−2, respectively for a selected study area between 62°N and 68°N in latitude and 125°W and 145°W in longitude over three mainly clear‐sky days (23–25 June). The derived diurnally averaged smoke aerosol shortwave radiative forcing is 19.9±12.1 W m−2 for a mean τ0.55 of 1.88±0.71 over the same time period. The derived ?F‐τ relationship can be implemented in the radiation scheme used in regional climate models to assess the effect of wildfire aerosols.