Using Spaceborne Aerosol Observations to Constrain Biomass Burning Emissions in the GOCART Model

Biomass burning has been recognized as a major contributor to atmospheric concentrations of carbonaceous aerosol, dominant in some locations and seasons. Simulations of biomass burning (BB) emissions in global chemistry transport models strongly depend on the inventories that define emission source location and strength. There are several global biomass burning emission products having different spatial and temporal resolutions. All these inventories can be used with global CTMs, but their estimates of aerosol emissions differ, often by factors of 2 or 3 for a given region. Such variability in emission amounts inevitably leads to discrepancies in the magnitudes of simulated aerosol effects. We use total column aerosol optical depth (AOD) observed by the MODIS and MISR instruments on the Terra satellite, and MODIS on Aqua, to provide top-down constraints on the strength of biomass burning emission sources. We chose several burning events during 2006, in different places on the Earth, to develop and test the feasibility of our approach, and use the GOCART model as the main tool to simulate BB aerosols, their emission, evolution, transport and removal. The diversity in aerosol optical depth as a result of using different emission inputs is presented for these events, along with the space-borne maps of total-column AOD used as reference, and as instantaneous constraints on integrated source strength. Additional constraints on the simulated emission injection height, evolution and transport of the smoke plumes are provided by plume heights observed from MISR, and the aerosol layer heights detected by CALIOP instrument on CALIPSO satellite. These data are used to validate or adjust simulated emission injection height for the study cases. Detailed analysis of select cases will be presented as well as a summary of all analyzed fire events.