TM5

The figure above shows OMI observed and TM5 modeled NO₂ tropospheric columns as well as MODIS Terra + Aqua cloud corrected monthly fire counts (MOD14CMH + MYD14CMH) for July-September, 2005, a year of severe drought for the Amazon.  Observed and modeled NO₂ concentration enhancements correlate well spatially and temporally with observed active fires.  However, in July, TM5 tends to under predict OMI NO₂ columns, while in August and September TM5 NO₂ columns are higher than observations by more than a factor of 2 in central Brazil and Bolivia; areas where deforestation is the primary source of fire emissions.  Our modeling suggests that NO_x emission factors for deforestation burning were significantly lower than conventional estimates used in bottom-up fire emissions modeling, possibly because prolonged dry spells led to a larger contribution of smoldering combustion from large diameter fuels.