Satellite Measurements of Carbonyl Sulfide Constrain Model Estimates of Tropical Carbon Uptake

Carbon uptake via photosynthesis (gross primary production, or GPP) is a critical component of global climate models. Model estimates of GPP are highly varied in the tropics, with observational constraints hampered by sparse sampling sites and frequent cloud cover. Atmospheric carbonyl sulfide, which has previously been used to constrain GPP over North America, holds potential as a remote tracer of GPP in the tropics. Using satellite observations from the MIPAS instrument and a range of model scenarios, we demonstrate the use of remotely-sensed carbonyl sulfide as a constraint on GPP in the Amazon basin. While uncertainties remain, preliminary results suggest lower-than-average GPP models are more consistent with observations. This work was performed in part under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.