HR: 1340h
AN: A33A-0827    [Abstracts]
TI: 2D and 3D Eulerian Simulations of the Dynamics and Gas and Aerosol Chemistry of a Young Biomass Burning Smoke Plume from a Savannah Fire
AU: * Alvarado, M J
EM: mjalvara@mit.edu
AF: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139,
AU: Prinn, R G
EM: rprinn@mit.edu
AF: Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139,
AB: The growth of aerosol particles and production of ozone in young smoke plumes is the result of a complex interaction between the mean flow in the smoke plume, turbulent diffusion, gas-phase oxidation, coagulation, and mass transfer between phases. Models allow us to separate the effects of these processes and predict their impact on the global environment. We present the results of two and three-dimensional Eulerian simulations of the dynamics and chemistry of the smoke plume formed by the Timbavati savannah fire studied during SAFARI 2000 (Hobbs et al., 2003, JGR, doi:10.1029/2002JD002352). The dynamical model is an extension of an Eulerian cloud-resolving model that has previously been used to study the role of deep convective clouds on tropospheric chemistry (Wang and Prinn, 2000, JGR, 105(D17) 22,269-22,297). The model includes a source of sensible heat, gases, and particles at the surface to simulate the savannah fire. The new gas and aerosol chemistry model includes heterogeneous chemistry, kinetic mass transfer, coagulation and the formation of secondary organic and inorganic aerosol. Photolysis rates are calculated based on the solution of the radiative transfer equation within the plume, including the scattering and absorption of radiation by the smoke aerosols. Our preliminary 2D Eulerian results using standard chemistry and UV fluxes show that the model can simulate the lower but not the higher levels of O₃ observed. Also, the simulated 2D O₃ field shows a wave-like pattern in the downwind direction, even though the emissions from the fire are held constant. This suggests that plume heterogeneity in the downwind direction may account for some of the observed variability in O₃. We will present results of runs incorporating higher resolution calculation of photolysis rates, heterogeneous HONO formation, and gas phase reactions involving the uncharacterized organic compounds observed in the gas phase of the Timbavati plume in order to better simulate these higher O₃ values.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0317 Chemical kinetic and photochemical properties
DE: 0368 Troposphere: constituent transport and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting