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Abstract Orbital precession has been linked to glacial cycles and the atmospheric carbon dioxide (CO2) concentration, yet the direct impact of precession on the carbon cycle is not well understood. We analyze output from an Earth system model configured under different orbital parameters to isolate the impact of precession on air‐sea CO2flux in the Southern Ocean—a component of the global carbon cycle that is thought to play a key role on past atmospheric CO2variations. Here, we demonstrate that periods of high precession are coincident with anomalous CO2outgassing from the Southern Ocean. Under high precession, we find a poleward shift in the southern westerly winds, enhanced Southern Ocean meridional overturning, and an increase in the surface ocean partial pressure of CO2along the core of the Antarctic Circumpolar Current. These results suggest that orbital precession may have played an important role in driving changes in atmospheric CO2.
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Extratropical storms induce carbon outgassing over the Southern Ocean
Abstract The strength and variability of the Southern Ocean carbon sink is a significant source of uncertainty in the global carbon budget. One barrier to reconciling observations and models is understanding how synoptic weather patterns modulate air-sea carbon exchange. Here, we identify and track storms using atmospheric sea level pressure fields from reanalysis data to assess the role that storms play in driving air-sea CO2exchange. We examine the main drivers of CO2fluxes under storm forcing and quantify their contribution to Southern Ocean annual air-sea CO2fluxes. Our analysis relies on a forced ocean-ice simulation from the Community Earth System Model, as well as CO2fluxes estimated from Biogeochemical Argo floats. We find that extratropical storms in the Southern Hemisphere induce CO2outgassing, driven by CO2disequilibrium. However, this effect is an order of magnitude larger in observations compared to the model and caused by different reasons. Despite large uncertainties in CO2fluxes and storm statistics, observations suggest a pivotal role of storms in driving Southern Ocean air-sea CO2outgassing that remains to be well represented in climate models, and needs to be further investigated in observations.
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- PAR ID:
- 10508574
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- npj Climate and Atmospheric Science
- Volume:
- 7
- Issue:
- 1
- ISSN:
- 2397-3722
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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