# Carbon isotope evidence for the latitudinal distribution and wind speed dependence of the air–sea gas transfer velocity

Author(s) Krakauer, Nir Y., Randerson, James T., Primeau, François W., Gruber, Nicolas, Menemenlis, Dimitris
Publication Type Journal Items, Publication Status: Published
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Title Carbon isotope evidence for the latitudinal distribution and wind speed dependence of the air–sea gas transfer velocity
Author(s) Krakauer, Nir Y.
Randerson, James T.
Primeau, François W.
Gruber, Nicolas
Menemenlis, Dimitris
Journal or Series Title Tellus. Series B, Chemical and physical meteorology
Volume Number 58
Issue Number 5
Start Page 390
End Page 417
ISSN 0280-6509
1600-0889
Publisher Wiley-Blackwell
Publication Place Copenhagen
Publication Date 2006-11
Abstract The air–sea gas transfer velocity is an important determinant of the exchange of gases, including CO2, between the atmosphere and ocean, but the magnitude of the transfer velocity and what factors control it remains poorly known. Here, we use oceanic and atmospheric observations of 14C and 13C to constrain the global mean gas transfer velocity as well as the exponent of its wind speed dependence, utilizing the distinct signatures left by the air–sea exchange of 14CO2 and 13CO2. While the atmosphere and ocean inventories of 14CO2 and 13CO2 constrain the mean gas transfer velocity, the latitudinal pattern in the atmospheric and oceanic 14C and 13C distributions contain information about the wind speed dependence. We computed the uptake of bomb 14C by the ocean for different transfer velocity patterns using pulse response functions from an ocean general circulation model, and evaluated the match between the predicted bomb 14C concentrations and observationally based estimates for the 1970s–1990s. Using a wind speed climatology based on satellite measurements, we solved either for the best-fit global relationship between gas exchange and mean wind speed or for the mean gas transfer velocity over each of 11 ocean regions. We also compared the predicted consequences of different gas exchange relationships on the rate of change and interhemisphere gradient of 14C in atmospheric CO2 with tree-ring and atmospheric measurements. Our results suggest that globally, the dependence of the air–sea gas transfer velocity on wind speed is close to linear, with an exponent of 0.5 ± 0.4, and that the global mean gas transfer velocity at a Schmidt number of 660 is 20 ± 3 cm/hr, similar to the results of previous analyses. We find that the air–sea flux of 13C estimated from atmosphere and ocean observations also suggests a lower than quadratic dependence of gas exchange on wind speed.
DOI 10.1111/j.1600-0889.2006.00223.x
Additional Notes Manuscript received 13 January 2006, In final form 11 July 2006
Document Type Article
Publication Status Published
Language English
Assigned Organisational Unit(s) 03267
03731
Organisational Unit(s)
NEBIS System Number 000017639
Source Database ID PP-26969
WOS-000241347500008
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@article{Krkr2006,
author = "Krakauer, Nir Y. and Randerson, James T. and Primeau, Fran{\c{c}}ois W. and Gruber, Nicolas and Menemenlis, Dimitris",
title = "{C}arbon isotope evidence for the latitudinal distribution and wind speed dependence of the air{\textendash}sea gas transfer velocity",
journal = "Tellus. Series B, Chemical and physical meteorology",
year = 2006,
volume = "58",
number = "5",
pages = "390--417",
month = nov,
}


E-Citations record created: Thu, 01 Apr 2010, 17:20:24 CET