Study of Biomass Burning Emissions in Africa with MetOp-A/IASI
Thonat, Thibaud1; Crevoisier, Cyril1; Scott, Noelle1; Chédin, Alain1; Armante, Raymond1; Crépeau, Laurent2

Biomass burning is an important source of CO2, CO and CH4 to the atmosphere, and largely contributes to the interannual variations of their concentrations. This is especially true in Africa where some of the strongest emissions occur. However, there are still large discrepancies between existing emission inventories, stressing the need of diverse approaches to improve our knowledge of biomass burning emissions. The Infrared Atmospheric Sounding Interferometer (IASI) onboard the MetOp-A satellite launched in October 2006 enables to observe CO2, CO and CH4 twice a day, at 09:30 LT (day) and 21:30 LT (night), and to study correlations between their atmospheric distribution that may provide important information on the role of fires on the evolution of these gases. Here, we focus on South Africa and derive monthly mean tropospheric mixing ratios of each gas in clear sky conditions over 6 years (July 2007-June 2013). Following Chédin et al. (2005) who revealed the existence of a daily tropospheric excess of CO2 (DTE) quantitatively related to fire emissions in the tropics, we focus our analysis on the day minus night differences of CO and CO2, and show that their diurnal variations are in good agreement with the location of fires. For several areas classified by their types of vegetation, IASI CO and CO2 are in good agreement with fire products such as Fire Radiative Power (FRP), MODIS Burned Areas and fire emissions from inventories (GFEDv2,3), with a maximum in September and a length of the fire season of 5 months (May to October). The simultaneous use of CO and CO2 enables the characterization of fire emissions during both the smoldering and flaming phases, highlighting their differences in terms of vertical transport of emissions.