Quantification of modeled atmospheric CO2 uncertainty from various sources using ACT-America aircraft data
Abstract
The North American land sink plays an important role in the global carbon cycle, partially offsetting emissions from fossil fuel consumption and land use change. However, biogenic carbon flux estimates over North America from atmospheric inversions and terrestrial biogeochemical models remain highly uncertain. Top-down estimates are impacted by limited atmospheric data, uncertain prior flux estimates and errors in the atmospheric transport models, while bottom-up fluxes are affected by uncertain driver data, uncertain model parameters and missing mechanisms across ecosystems.
The Atmospheric Carbon and Transport (ACT) - America project collected a unique set of atmospheric mole fraction observations using airborne and ground-based platforms, aimed at improving the accuracy, precision and resolution of regional atmospheric inverse estimates of CO2 and CH4 sources and sinks. Here we use an ensemble-based mesoscale modeling system to quantify the modeled atmospheric CO2 uncertainty from different components, i.e., biospheric fluxes, transport, fossil fuel emissions, and boundary conditions, and evaluate the realism of elements of the ensemble by comparing model and observations. This ensemble modeling system comprises biospheric fluxes from an ensemble of biogeochemical simulations, fossil fuel emission products, global CO2 simulations, and atmospheric transport realizations. For the first time, a comprehensive analysis of uncertainties has been conducted to identify the structure in both space and time of each component. The ACT-America aircraft data along with surface tower and long-term aircraft profile measurements will be used to reveal model-data discrepancies across seasons and regions, and within both stormy- and fair-weather conditions. We describe how correlated error structures interfere at different levels of the optimization problem, limiting our ability to differentiate some of them, and highlight the potential of using spatially-extensive airborne, and temporally extensive tower measurements to reducing identify and minimize these errors.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.A41C..05F
- Keywords:
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- 0315 Biosphere/atmosphere interactions;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0322 Constituent sources and sinks;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0414 Biogeochemical cycles;
- processes;
- and modeling;
- BIOGEOSCIENCESDE: 0428 Carbon cycling;
- BIOGEOSCIENCES