Spatial and seasonal variability of the air-sea equilibration timescale of carbon dioxide
Abstract
Abstract The exchange of carbon dioxide between the ocean and the atmosphere tends to bring waters within the mixed layer toward equilibrium by reducing the partial pressure gradient across the air‐water interface. However, the equilibration process is not instantaneous; in general, there is a lag between forcing and response. The timescale of air‐sea equilibration depends on several factors involving the depth of the mixed layer, wind speed, and carbonate chemistry. We use a suite of observational data sets to generate climatological and seasonal composite maps of the air‐sea equilibration timescale. The relaxation timescale exhibits considerable spatial and seasonal variations that are largely set by changes in mixed layer depth and wind speed. The net effect is dominated by the mixed layer depth; the gas exchange velocity and carbonate chemistry parameters only provide partial compensation. Broadly speaking, the adjustment timescale tends to increase with latitude. We compare the observationally derived air‐sea gas exchange timescale with a model‐derived surface residence time and a data‐derived horizontal transport timescale, which allows us to define two nondimensional metrics of equilibration efficiency. These parameters highlight the tropics, subtropics, and northern North Atlantic as regions of inefficient air‐sea equilibration where carbon anomalies are relatively likely to persist. The efficiency parameters presented here can serve as simple tools for understanding the large‐scale persistence of air‐sea disequilibrium of CO 2 in both observations and models.
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The equilibration timescale for added alkalinity is longer than that for the atmospheric pCO2 perturbation from anthropogenic emissions, which has a global average equilibration time of approximately 1 year.
“This equilibration timescale is longer than that for the atmospheric pCO2 perturbation from anthropogenic emissions, where the global average equilibration time is approximately 1 year. 60”
From A framework for understanding efficiency losses of Ocean Alkalinity Enhancement (2026) · cites this paper as [60]
The Results (p. 6) say the air–sea CO₂ exchange timescale is often presented as approximately one year globally, supporting the cited comparison’s reference value. But the paper’s own area-weighted global mean is 4.4 months (section 3.1, p. 6); it does not establish the comparison with added alkalinity or identify that one-year value specifically with perturbations from anthropogenic emissions. (LLM, conf=0.88)
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References 47 · Cited by 211
Research works printed but not linked: 20
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- Authors
- Jones, D. C., Ito, T., Takano, Y., & Hsu, W.
- Affiliations
- Georgia Institute of Technology (US)
- Venue
- Global Biogeochemical Cycles
- Publisher
- American Geophysical Union (AGU)
- Published
- 2014-11
- Volume
- 28
- Issue
- 11
- Pages
- 1163-1178
- ISSN
- 0886-6236 (ISSN-L)
- 1944-9224
- OpenAlex
- W2165563340
- Cited by
- 211
- References
- 47
- Citations by year
- 2026: 27 · 2025: 32 · 2024: 48 · 2023: 49 · 2022: 20 · 2021: 4 · 2020: 9 · 2019: 3 · 2018: 10 · 2017: 2 · 2016: 6 · 2015: 1
- FWCI
- 2.16
- Type
- journal article
- Language
- en
- Open access
- closed
- Locations
- Global Biogeochemical Cycles (publishedVersion)
- NERC Open Research Archive (Natural Environment Research Council) (acceptedVersion)
- Funders
- NSF (OCE-1242313, OPP-1142009)
- NOAA USA (NA08OAR4320893)
- NERC UK (NE/J007757/1)
- Topics
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Marine and coastal ecosystems
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Oceanographic and Atmospheric Processes
- Physical Sciences › Earth and Planetary Sciences › Oceanography › Ocean Waves and Remote Sensing
- Keywords
- carbon dioxide, air-sea CO2 flux, mixed layer depth, wind speed, carbonate chemistry, surface residence time, seasonal variation, spatial variability
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