A Practical bi-parameter formula of gas transfer velocity depending on wave states

Physical Oceanography Laboratory, Ocean University of China, Qingdao, 266100 China
Journal of Oceanography (Impact Factor: 1.27). 10/2010; 66(5):663-671. DOI: 10.1007/s10872-010-0054-4


The parameter that describes the kinetics of the air-sea exchange of a poorly soluble gas is the gas transfer velocity which
is often parameterized as a function of wind speed. Both theoretical and experimental studies suggest that wind waves and
their breaking can significantly enhance the gas exchange at the air-sea interface. A relationship between gas transfer velocity
and a turbulent Reynolds number related to wind waves and their breaking is proposed based on field observations and drag
coefficient formulation. The proposed relationship can be further simplified as a function of the product of wind speed and
significant wave height. It is shown that this bi-parameter formula agrees quantitatively with the wind speed based parameterizations
under certain wave age conditions. The new gas transfer velocity attains its maximum under fully developed wave fields, in
which it is roughly dependent on the square of wind speed. This study provides a practical approach to quantitatively determine
the effect of waves on the estimation of air-sea gas fluxes with routine observational data.

KeywordsGas transfer velocity-wind speed-wind wave-significant wave height

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Available from: Lian Xie, Oct 06, 2015
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    • "In this article, uncertainty in CO 2 flux due to transfer velocity is estimated using data from TOPEX/Poseidon for the entire year 2000. Various wind-speed-dependent CO 2 transfer velocities (Liss and Merlivat 1986; Wanninkhof 1992; Wanninkhof and McGillis 1999; Wanninkhof et al. 2009; Jacobs, Kohsiek, and Oost 1999; Nightingale et al. 2000; Nightingale, Liss, and Schlosser 2000; McGillis et al. 2001, 2004; Kuss, Nagel, and Schneider 2004; Ho et al. 2006; Weiss et al. 2007; Sweeney et al. 2007; Asher 2009; Takahashi et al. 2009; Prytherch et al. 2010; Sarma et al. 2010) and sea-state-dependent parameterizations (Frew et al. 2007; Zhao and Xie 2010) are used to calculate the uncertainty. Global distributions of air–sea CO 2 transfer velocity and flux are retrieved. "
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    ABSTRACT: From TOPEX/Poseidon data, the significant uncertainty in global air-sea carbon dioxide (CO2) flux in 2000 is calculated from 21 wind-speed-dependent and 5 sea-state-dependent CO2 transfer velocities and the sea-to-air partial pressure difference Delta p(CO2) proposed by Takahashi, Sutherland, and Kozyr (2010). The sea-state-dependent parameterizations are calculated based on the significant wave height (SWH) and the radar backscatter coefficient sigma(0) measured using the Ku-band altimeter. Uncertainty in air. sea CO2 flux is compared using 26 various transfer velocity formulas. The maximum differences in global monthly mean and 4 degrees zonal mean values for gas transfer velocity among these formulas are 33.20 and 108.20 cm hour (1), respectively. The corresponding differences for sea-to-air CO2 flux are 6.41 and 0.58 Pg C year (1), respectively. Monthly mean global maps of gas transfer velocity and flux are also presented. The average value of the global mean, transfer velocity obtained using the 26 formula is 27.33 +/- 9.75 cm hour (1), and the averaged total global net air-to-sea CO2 flux is 2.77 +/- 1.02 Pg C year (1) after area weighting and Schmidt number correction. The sea-state-dependent parameterizations are near these values, providing a successful method to estimate the air. sea CO2 transfer velocity and flux.
    International Journal of Remote Sensing 06/2014; 35(11-12):4340-4370. DOI:10.1080/01431161.2014.916046 · 1.65 Impact Factor
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    • "There are more physical phenomena that affect the water-side transfer velocity and for which there have been proposed algorithms to simulate them. Such are the cases of the formation of bubbles with high wind speeds and breaking waves (Memery and Merlivat, 1985; Woolf, 1997, 2005; Zhao et al., 2003; Duan and Martin, 2007), wave field (Taylor and Yelland, 2001; Oost et al., 2002; Fairall et al., 2003; Hwang, 2005; Zhao and Xie, 2010), rain (Ho et al., 2004; Zappa et al., 2009; Turk et al., 2010), surfactants (Frew et al., 2004) and the variability of the wind velocity over longer time intervals (Wanninkhof, 1992). The parameterization by Fairall et al. (2000) attempts to congregate the fundamental environmental factors over the open ocean. "
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    ABSTRACT: A numerical tool was developed for the estima-tion of gas fluxes across the air–water interface. The primary objective is to use it to estimate CO 2 fluxes. Nevertheless ap-plication to other gases is easily accomplished by changing the values of the parameters related to the physical properties of the gases. A user-friendly software was developed allow-ing to build upon a standard kernel a custom-made gas flux model with the preferred parameterizations. These include single or double layer models; several numerical schemes for the effects of wind in the air-side and water-side transfer ve-locities; the effects of atmospheric stability, surface rough-ness and turbulence from current drag with the bottom; and the effects on solubility of water temperature, salinity, air temperature and pressure. An analysis was also developed which decomposes the difference between the fluxes in a ref-erence situation and in alternative situations into its several forcing functions. This analysis relies on the Taylor expan-sion of the gas flux model, requiring the numerical estima-tion of partial derivatives by a multivariate version of the col-location polynomial. Both the flux model and the difference decomposition analysis were tested with data taken from sur-veys done in the lagoon system of Ria Formosa, south Por-tugal, in which the CO 2 fluxes were estimated using the in-frared gas analyzer (IRGA) and floating chamber method, whereas the CO 2 concentrations were estimated using the IRGA and degasification chamber. Observations and estima-tions show a remarkable fit.
    Ocean Science 01/2013; 9(2):355-375. DOI:10.5194/os-9-355-2013 · 2.23 Impact Factor
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    ABSTRACT: Using data from the European remote sensing scatterometer (ERS-2) from July 1997 to August 1998, global distributions of the air-sea CO2 transfer velocity and flux are retrieved. A new model of the air-sea CO2 transfer velocity with surface wind speed and wave steepness is proposed. The wave steepness (δ) is retrieved using a neural network (NN) model from ERS-2 scatterometer data, while the wind speed is directly derived by the ERS-2 scatterometer. The new model agrees well with the formulations based on the wind speed and the variation in the wind speed dependent relationships presented in many previous studies can be explained by this proposed relation with variation in wave steepness effect. Seasonally global maps of gas transfer velocity and flux are shown on the basis of the new model and the seasonal variations of the transfer velocity and flux during the 1 a period. The global mean gas transfer velocity is 30 cm/h after area-weighting and Schmidt number correction and its accuracy remains calculation with in situ data. The highest transfer velocity occurs around 60°N and 60°S, while the lowest on the equator. The total air to sea CO2 flux (calculated by carbon) in that year is 1.77 Pg. The strongest source of CO2 is in the equatorial east Pacific Ocean, while the strongest sink is in the 68°N. Full exploration of the uncertainty of this estimate awaits further data. An effectual method is provided to calculate the effect of waves on the determination of air-sea CO2 transfer velocity and fluxes with ERS-2 scatterometer data.
    Acta Oceanologica Sinica -English Edition- 07/2013; 32(7). DOI:10.1007/s13131-013-0334-0 · 0.75 Impact Factor
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