CO over South America Modeling inter annual variability of biomass burning emissions Pim Hooghiemstra & Maarten Krol 28 November 2011 – TM meeting
Motivation Inter annual variability is observed in MOPITT columns over the Amazon region.
Goal Robust monthly total CO emissions on high resolution for 2006 – 2010 over South America Using TM5-4D-Var with 1 o x1 o zoom over South America Prior from EDGARv4.1, GFED3.1, TM4-Crete MOPITT columns / NOAA surface observations
Prior simulation vs observations Emissions seem too low a priori (large region) Over main BB regions, prior is too high in 2007 and 2010
Posterior fit with MOPITT 4D-Var system brings model simulation close to observations. Fit is very good for large regions, a bit less for small regions.
Emissions 1 o x1 o region Large variability in emissions from year to year Emissions increase for all months
Spatial patterns 2007 & 2010: Emissions go down for deforestation regions Brazil Other years, emissions increase (both BB and other sources)
Validation with NOAA Much too high => assimilate NOAA obs also
Bias correction A bias correction is needed to fit NOAA and MOPITT
Fit with data Fit with NOAA improves greatly! Fit with MOPITT remains good!
Effect on inferred emissions Effect is only small
Sensitivity studies Emission estimates are robust Using GFED for 2010 makes a large difference NOAA only inversion yields too high biomass burning emissions in September and too low background emissions
Conclusions (1) Robust IAV in BB emissions: Peak month emissions vary from 28 Tg CO in 2009 to 67 Tg CO in BB emissions of GFED3.1 are too high in main deforestation regions in Brazil in 2007 & In other years, GFED3.1 seems a bit too low. Remark: difficult to quantify, we only optimize total. What about errors in the model?
Conclusions (2) Inferred emissions sensitive to total prior BB emission. Bias correction is necessary to fit both MOPITT & NOAA observations. No significant difference in optimized emissions and fit with MOPITT, fit with NOAA improves significantly.