Atmospheric Tomography Mission: The global carbonyl sulfide budget

DESCRIPTION: The NASA ATom mission provides unprecedented observations of atmospheric trace gases throughout the remote atmosphere. We will use the ATom OCS data, to provide an independent estimate of the global carbon land sink for the ATom time periods, including the 2015/2016 El Nino. In the boundary layer, OCS is a tracer for ecosystem scale stomatal conductance (activity of vegetation) and has been used in regional analysis to quantify the regional carbon land sink. To widen the analysis to the global scale, we need to more tightly constrain the marine source of OCS. Current estimates of the ocean source of OCS vary between 200 and 800 TgS yr-1, which could be much better constrained using ATom data. Preliminary analysis of ATom OCS data in the clean marine boundary layer suggests concentrations on the lower end of the range. We will update the OCS source fluxes in the Geos-Chem chemistry transport model and use the ATom OCS data (along with other tracers) to determine the source of the large mismatch in the OCS budget.