Comparing the Impact of Boreal Wildfires on Radiation, Clouds and Precipitation in Northern America and Russia

The boreal forest covers a vast region of 1.2 billion hectares, spanning across North America and Russia. Wildfires frequently occurring in the boreal forest may have significant implications for weather and climate, but they remain poorly understood. An additional complexity is that wildfires in North America differ from those in Russia in terms of their duration, fire radiative power, density of active fires, and intensity of smoke emissions. In this study, we investigate the potential effect of these differences on smoke-radiation-cloud-precipitation interactions by examining actual wildfire cases, including the 2007 Central Canada wildfires and the 2002 Yakutsk wildfires. We use the fully coupled mesoscale model WRF-Chem-SMOKE in conjunction with satellite observations. Analyzed satellite data include MODIS aerosol and cloud products, NASA/GEWEX Surface Radiation Budget (SRB) SW/LW fluxes, and the Clouds and the Earth's Radiant Energy System (CERES) SW/LW fluxes. Additionally satellite products are used to compute smoke emissions which are incorporated “on-line” at the hourly time step in WRF-Chem-SMOKE. Smoke particles are size- and composition-resolved in the model and can serve as CCN or IN. Smoke affects the radiative balance by scattering and absorbing SW radiation or through smoke-induced changes in the properties of clouds. We present an in-depth analysis of smoke-induced changes in the surface downward and TOA upward SW fluxes, cloud properties (liquid water path, ice water path, etc.), and precipitation, addressing the region-specific features of considered wildfires.