Interannual variability (IAV) is a key component of the global carbon cycle. Satellite observations from OCO-2 provide exciting new insight into terrestrial and marine CO2 budgets as well as IAV.…

This is a $568,011.92 grant awarded to The Johns Hopkins University by the National Aeronautics and Space Administration (NASA) Shared Services Center on July 19, 2018. The grant supports research on interannual variability in the global carbon cycle, using data from NASA's Orbiting Carbon Observatory-2 (OCO-2) and the Greenhouse Gases Observing Satellite (GOSAT).

The research aims to estimate multiple years of global terrestrial and marine CO2 fluxes, diagnose and quantify the effects of model and measurement errors, and explore the relationships between environmental drivers like solar-induced fluorescence (SIF) and CO2 fluxes. This work will advance scientific understanding of the global carbon cycle and improve terrestrial biosphere model estimates of CO2 budgets and interannual variability. The grant has a period of performance ending on October 11, 2022, and does not have a set-aside designation.

Interannual variability (IAV) is a key component of the global carbon cycle. Satellite observations from OCO-2 provide exciting new insight into terrestrial and marine CO2 budgets as well as IAV. Its potential is two-fold. First, IT and the gosat satellite observe CO2 broadly across the globe, including regions with in situ observations. Second, these satellites observe SIF, and SIF could be a powerful proxy for IAV. We will estimate multiple years of global terrestrial and marine CO2 fluxes using OCO-2 and gosat observations paired with a geostatistical inverse model (GIM). We will also robustly diagnose and quantify the effects of model and measurement/retrieval errors using multiple atmospheric transport models and multiple types of satellite and in situ observations. The proposed research will further provide a novel link between top-down, satellite-based flux estimates and the environmental drivers like SIF that are integral to bottom-up models and thus integral to a process-based understanding of CO2 fluxes; we will use the GIM to quantify the relationships between environmental driver data and CO2 fluxes, and we will compare and contrast these relationships with those in state-of-the-art process-based flux models. This research will advance scientific knowledge of the global carbon cycle using emergent satellite observations with broad global coverage. The results will indicate the sensitivity of terrestrial and marine CO2 fluxes to year-to-year variations in environmental conditions. Furthermore, this work will facilitate a better understanding of the environmental drivers of CO2 fluxes. IT will thus help improve TBM estimates of CO2 budgets and IAV and will contribute to more confident future carbon cycle projections.