A Comparison of Satellite-Retrieved, Modeled, and Measured NH3/CO Ratios in Biomass Burning Plumes

The atmospheric distributions of carbon monoxide (CO) and ammonia (NH₃) are of interest for several reasons. CO is a primary pollutant, an ozone precursor, an atmospheric tracer with a lifetime of a few months, and the most important sink for the hydroxyl radical - the atmosphere's detergent. Its sources include fossil fuel use, oxidation of biogenic hydrocarbons, methane oxidation, and biomass burning. NH₃ is the primary gaseous base found in the atmosphere and reacts rapidly with sulfuric and nitric acids to form PM_2.5. Its major sources include the decay of domestic livestock waste, volatilization losses from fertilizers, decomposition of organic material in soils by organisms, and biomass burning. The lifetime of NH₃ in the atmosphere is highly variable but is typically on the order of a day due to its source distribution and high deposition velocity. The ratio of NH₃ / CO is useful because it can be used to gain insight into the relative emissions of NH₃ and CO, the age of a plume, and the contribution of biomass burning to trends in CO. In this presentation we will compare satellite-retrieved, modeled, and measured NH₃, CO, and NH₃ / CO ratios in selected biomass burning plumes during the September 2002 to August 2016 time period. Biomass burning emissions of CO and NH₃ from the GFED and QFED emission inventories and aerosol index (AI) retrievals from TOMS and OMI will be used to locate the plumes. The analysis will use CO retrievals from MOPITT, CO and NH₃ retrievals from AIRS, CO and NH₃ profiles from a recent ~0.625° x 0.5° atmospheric composition simulation with the NASA Global Modeling Initiative (GMI) model that includes the GOCART aerosol module constrained by replay meteorological fields from the NASA MERRA-2 reanalysis, and measurements from NOAA and NASA field campaigns. The preliminary analysis compares the ratios of NH₃ and CO in major biomass burning events as part of an examination of the usefulness of satellite-retrieved, modeled, and measured NH₃/ CO ratios for evaluating emission inventories, the age of biomass burning plumes, variations in the nitrogen content of biomass burning plumes between agricultural burning and wildfires, and the export of biomass burning plumes to the free troposphere.