CAN WE BRING DISCIPLINE TO CARBON CYCLE MODELING USING OBSERVATIONS OF SOLAR INDUCED FLUORESCENCE AND CARBONYL SULFIDE?

Abstract:

Recent model intercomparisons in the CMIP5 study showed that carbon-climate feedback is an major source of uncertainty in projections of future greenhouse gas forcing and climate change. Large disagreement between different terrestrial carbon cycle models in the simulation of photosynthesis and respiration is at the root of this problem, and an important cause of this uncertainty is that the modeling is being done without knowing the correct answer. Synoptic scale modeling of the carbon cycle is actually an extrapolation based studies conducted at smaller scales. CO2 observations from OCO-2 and the global networks can provide an important overall constraint at this scale, but the models need information on the gross fluxes associated with photosynthesis and respiration - not just their sum. At least one other independent measurement is needed to constrain this system. Recent advances in two areas 1) remote sensing of Solar Induced chlorophyll Fluorescence (SIF) from space, and 2) in measurements of the spatial dynamics of atmospheric OCS have the potential to provide this additional constraint. Modeling studies described here are designed to prepare for a test of this approach within the context of the upcoming ACT-America campaign.