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Gas-aerosol partitioning of ammonia in biomass burning plumes: Implications for the interpretation of spaceborne observations of ammonia and the radiative forcing of ammonium nitrate

par Paulot, F.;Paynter, D.;Ginoux, Paul ;Naik, Vaishali;Whitburn, Simon ;Van Damme, Martin ;Clarisse, Lieven ;Coheur, Pierre ;Horowitz, L. W.
Référence Geophysical research letters, 44, 15, page (8084-8093)
Publication Publié, 2017-08

Article révisé par les pairs

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Résumé :

Satellite-derived enhancement ratios of NH3 relative to CO column burden (ERNH3/CO) in fires over Alaska, the Amazon, and South Equatorial Africa are 35, 45, and 70% lower than the corresponding ratio of their emissions factors (ERNH3/CO) from biomass burning derived from in situ observations. Simulations performed using the Geophysical Fluid Dynamics Laboratory AM3 global chemistry-climate model show that these regional differences may not entirely stem from an overestimate of NH3 emissions but rather from changes in the gas-aerosol partitioning of NH3 to NH4 +. Differences between (ERNH3/CO) and (EFNH3/CO) are largest in regions where is high, consistent with the production of NH4NO3. Biomass burning is estimated to contribute 11–23% of the global burden and direct radiative effect (DRE) of NH4NO3 (−15 to −28 mW m−2), despite accounting for less than 6% of the global source of NH3. Production of NH4NO3 is largely concentrated over the Amazon and South Equatorial Africa, where its DRE can reach −1.9 W m−2 during the biomass burning season.