Quantification of regional and global radiative impacts and climate effects of tropical fire aerosols

Michael Tosca, UC Irvine, Dept. of Earth System Science, mtosca@uci.edu (Presenter)
James T. Randerson, UC Irvine, Dept. of Earth System Science, jranders@uci.edu
Charles Zender, UC Irvine, Dept. of Earth System Science, zender@uci.edu

Regionally expansive smoke clouds originating from deforestation fires in Indonesia can modify local precipitation patterns via direct aerosol scattering and absorption of solar radiation (Tosca et al., 2010). Here we quantified the global as well as regional climate impacts of fire aerosols for three tropical burning regions using the Community Atmosphere Model, version 5 (CAM5) coupled to a slab ocean model (SOM) embedded within the Community Earth System Model (CESM). In addition to direct aerosol radiative effects, CAM5 also quantified indirect, semi-direct and cloud microphysical aerosol effects. Climate impacts were determined using regionally adjusted emissions data that produced realistic aerosol optical depths in CAM5. We first analyzed a single 12-year transient simulation (1996-2007) forced with unadjusted emissions estimates from the Global Fire Emissions Database, version 3 (GFEDv3) and compared aerosol optical depths (AODs) for 4 different burning regions (equatorial Asia, southern Africa, South America and boreal North America) to observed MISR and MODIS AODs for the same period. Based on this analysis we adjusted emissions for each burning region between 150 and 300% and forced a second simulation with the regionally adjusted emissions. Improved AODs from this simulation were compared to AERONET observations available at 15 stations throughout the tropics. We then conducted two transient simulations—one with the adjusted fire emissions and one without fires to quantify the cumulative fire aerosol climate impact globally and for three major tropical burning regions (equatorial Asia, southern Africa and South America). Specifically, we quantified smoke effects on radiation, precipitation and temperature.

References

Tosca, M.G., J.T. Randerson, C.S. Zender, M.G. Flanner and P.J. Rasch (2010), Do biomass burning aerosols intensify drought in equatorial Asia during El Niño?, Atmos. Chem. Phys., 10, 3515-3528, doiL 10.5194/acp-10-3515-2010.

Presentation Type:  Poster

Session:  Coupled Processes at Land-Atmosphere-Ocean Interfaces   (Mon 4:00 PM)

Associated Project(s): 

• Randerson, Jim: Global Carbon Emissions from Fires: Improving our Understanding of Interactions between Land Use, Fires, and Climate Change ...details

Poster Location ID: 88