Monday, 17 November 2003: 11:00 AM
Atmospheric Response and Feedback to Smoke Radiative Forcing from Wildland Fires
Smoke from wildland fires over a large area can affect weather and climate by modifying regional and global radiaitive balance. An earlier estimate indicated a magnitude of the smoke radiative forcing comparable to that of anthropogenic sulfate aerosols. This could lead to remarkable changes in regional atmospheric circulations and precipitation. This study investigates regional atmospheric response and feedback to smoke direct radiative forcing from wildland fires using a dynamical model and a regional climate model. The analytical solutions of the dynamical model and numerical simulations with the regional climate model indicate that the absorption and reflection of fire smoke particles of solar radiation leads to the generation of PBL cooling, an anti-cyclonic circulation trend, and descending motions. Vertical turbulent transport of water vapor and clouds are reduced. The reduction in clouds, on the other hand, allows more solar radiation absorbed by the Earth-atmosphere system, which partially offsets the negative direct radiative forcing of smoke.