Evidence for wind‐pumping of air‐sea gas exchange based on direct measurements of CO₂ fluxes

Abstract

In a series of measurements of CO2 flux over the sea the mean flux was near zero, even though the surface water had substantially higher partial pressure of CO2 than the air. Hourly variations in wind speed were well correlated with the flux, suggesting that a wind‐driven process, such as wave breaking and downward mixing of bubbles, may drive additional CO2 into the water as the wind speed increases. The traditional model of air‐sea gas flux as a function of sea‐air partial pressure difference was modified to include downward pumping by wind. We conclude that the flux of nonatmospheric gases such as radon does not serve as a complete model for the two‐way surface flux of atmospheric constituents such as CO2.

Measurements of the Carbon Dioxide Flux over the Ocean

“…They concluded that the upward flux of carbon dioxide was attributable to seasonal warming with an associated reduction in the carbon dioxide solubility and an increase of the partial pressure of carbon dioxide in the sea water. Smith and Jones (1985) duplicated experiments at the same place in late autumn. Wesely el al.…”

Measurements of Carbon Dioxide Flux Over a Shallow Coastal Water

“…Recently, eddy correlation measurements of CO2 eddy flux were made over shallow coastal water (Jones and Smith, 1977;Wesely et al, 1982;Smith and Jones, 1985). It is interesting to note that the CO2 is transported upward over the sea water during summer months, and that upward fluxes are nearly proportional to friction velocity u*.…”

“…They concluded that the upward flux of CO2 was attributed to seasonal warming with an associated reduction in the CO2 solubility and an increase of the partial pressure of CO2 in the surface water. Smith and Jones (1985) duplicated experiments at the same place in late autumn to see the downward flux of CO2. Wesely et al (1982) measured the CO2 flux with the eddy correlation technique over the sea off the coast of Florida during a period of increasing sea surface temperature.…”

A Preliminary Review of Global CO2 Exchange Between Ocean and Atmosphere

“…As a minimum, reasonably accurate probability density functions should be used to calculate the average exchange coefficient, < E >. Beginning over a decade ago, turbulence measurements of CO 2 have developed slowly [91, [12], [17], [26] and generated sharp controversy. To the extent that they have been compared, the turbulent results exceed the bulk fluxes by factors of 5 to 10.…”