A comparison of atmospheric CO<sub>2</sub> flux signals obtained from GEOS-Chem flux inversions constrained by in situ or GOSAT observations

Abstract

Correspondence to: Saroja Polavarapu (saroja.polavarapu@canada.ca) Key points:1. The potential for GOSAT data to better resolve zonally asymmetric structures in the tropics year round and in the northern extratropics except during boreal winter is demonstrated.2. In the lower troposphere, zonal asymmetries in the flux signal exceed that arising from meteorological uncertainties 10 only in boreal summer, when in situ data constrain posterior fluxes.3. The GEOS-Chem flux inversion constrained by in situ data better agrees (by 0.5 ppm) with independent observations on the global annual scale compared to the inversion constrained with GOSAT observations but the inversion with GOSAT data better captures the seasonal cycle of CO 2 at northern extratropical sites. 15Keywords: data assimilation, carbon dioxide, GOSAT, CO 2 flux estimation, greenhouse gas sources and sinks, HIPPO, HIAPER Pole-to-Pole Observations, National ScienceFoundation, NSF, NSF/NCAR Gulfstream-V (GV).Atmos. such spatial structures will require a dense network of independent observations. Atmos. Chem. Phys. Discuss., https://doi

On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

“…CT2016 shows poor agreement with all proxies, indicating that this inversion is unable to isolate zonally asymmetric fluxes in the northern extratropics, which is surprising given the high sensitivity of the surface CO 2 network to northern extratropical surface fluxes (Byrne et al, 2017). However, consistent with this result, Polavarapu et al (2018) show that flux inversions assimilating measurements from the surface network are less able to recover zonally asymmetric flux signals than flux inversions assimilating GOSAT measurements. CT2016 also includes prior NEE IAV in the inversion, which may negatively impact the posterior NEE IAV, based on the GEOS-Chem inversion results.…”