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Abstract The Southern Ocean, an important region for the uptake of anthropogenic carbon dioxide (CO2), features strong surface currents due to substantial mesoscale meanders and eddies. These features interact with the wind and modify the momentum transfer from the atmosphere to the ocean. Although such interactions are known to reduce momentum transfer, their impact on air‐sea carbon exchange remains unclear. Using a 1/20° physical‐biogeochemical coupled ocean model, we examined the impact of the current‐wind interaction on the surface carbon concentration and the air‐sea carbon exchange in the Southern Ocean. The current‐wind interaction decreased winter partial pressure of CO2(pCO2) at the ocean surface mainly south of the northern subantarctic front. It also reducedpCO2in summer, indicating enhanced uptake, but not to the same extent as the winter loss. Consequently, the net outgassing of CO2was found to be reduced by approximately 17%when including current‐wind interaction. These changes stem from the combined effect of vertical mixing and Ekman divergence. A budget analysis of dissolved inorganic carbon (DIC) revealed that a weakening of vertical mixing by current‐wind interaction reduces the carbon supply from below, and particularly so in winter. The weaker wind stress additionally lowers the subsurface DIC concentration in summer, which can affect the vertical diffusive flux of carbon in winter. Our study suggests that ignoring current‐wind interactions in the Southern Ocean can overestimate winter CO2outgassing.
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Global Warming Pattern Formation: The Role of Ocean Heat Uptake
Abstract This study investigates the formation mechanism of the ocean surface warming pattern in response to a doubling CO2with a focus on the role of ocean heat uptake (or ocean surface heat flux change, ΔQnet). We demonstrate that thetransientpatterns of surface warming and rainfall change simulated by the dynamic ocean–atmosphere coupled model (DOM) can be reproduced by theequilibriumsolutions of the slab ocean–atmosphere coupled model (SOM) simulations when forced with the DOM ΔQnetdistribution. The SOM is then used as a diagnostic inverse modeling tool to decompose the CO2-induced thermodynamic warming effect and the ΔQnet(ocean heat uptake)–induced cooling effect. As ΔQnetis largely positive (i.e., downward into the ocean) in the subpolar oceans and weakly negative at the equator, its cooling effect is strongly polar amplified and opposes the CO2warming, reducing the net warming response especially over Antarctica. For the same reason, the ΔQnet-induced cooling effect contributes significantly to the equatorially enhanced warming in all three ocean basins, while the CO2warming effect plays a role in the equatorial warming of the eastern Pacific. The spatially varying component of ΔQnet, although globally averaged to zero, can effectively rectify and lead to decreased global mean surface temperature of a comparable magnitude as the global mean ΔQneteffect under transient climate change. Our study highlights the importance of air–sea interaction in the surface warming pattern formation and the key role of ocean heat uptake pattern.
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- PAR ID:
- 10364239
- Publisher / Repository:
- American Meteorological Society
- Date Published:
- Journal Name:
- Journal of Climate
- Volume:
- 35
- Issue:
- 6
- ISSN:
- 0894-8755
- Page Range / eLocation ID:
- p. 1885-1899
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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