ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-9-131-2009 The effects of experimental uncertainty in parameterizing air-sea gas exchange using tracer experiment data Asher W. E. 1 University of Washington, Seattle, Washington, USA 09 01 2009 9 1 131 139 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/9/131/2009/acp-9-131-2009.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/9/131/2009/acp-9-131-2009.pdf

It is not practical to measure air-sea gas fluxes in the open ocean for all conditions and areas of interest. Therefore, in many cases fluxes are estimated from measurements of air-phase and water-phase gas concentrations, a measured environmental forcing function such as wind speed, and a parameterization of the air-sea transfer velocity in terms of the environmental forcing function. One problem with this approach is that when direct measurements of the transfer velocity are plotted versus the most commonly used forcing function, wind speed, there is considerable scatter, leading to a relatively large uncertainty in the flux. Because it is known that multiple processes can affect gas transfer, it is commonly assumed that this scatter is caused by single-forcing function parameterizations being incomplete in a physical sense. However, scatter in the experimental data can also result from experimental uncertainty (i.e., measurement error). Here, results from field and laboratory results are used to estimate how experimental uncertainty contributes to the observed scatter in the measured fluxes and transfer velocities as a function of environmental forcing. The results show that experimental uncertainty could explain half of the observed scatter in field and laboratory measurements of air-sea gas transfer velocity.

 References Asher, W. E. and Litchendorf, T. M.: Visualizing near-surface CO2 concentration fluctuations using laser-induced fluorescence, Exp. in Fluids, doi:10.1007/s00348-008-0554-9, in press, 2009. Asher, W. E. and Pankow, J. F.: The effect of surface films on concentration fluctuations close to a gas/liquid interface, in: Air-Water Mass Transfer, edited by: Wilhelms, S. E., and Gulliver, J. S., American Society of Civil Engineering, New York, 68–80, 1991a. Asher, W. E. and Pankow, J. F.: Prediction of gas/water mass transport coefficients by a surface renewal model, Env. Sci. Tech., 25, 1294–1300, 1991b. Atmane, M. A., Asher, W. E., and Jessup, A. T.: On the use of the active infrared technique to infer heat and gas transfer velocities at the air-water free surface, J. Geophys. Res.-Oceans, 109 (C08S14), doi:10.1029/2003JC001805, 2004. Davies, J. T.: Turbulence Phenomena, Academic Press, New York, 412 pp., 1972. Frew, N. M., Goldman, J. C., Dennett, M. R., and Johnson, A. S.: Impact of phytoplankton-generated surfactants on air-sea gas exchange, J. Geophys. Res.-Oceans 95C, 3337–3352, 1990. Harriott, P.: A random eddy modification of the penetration theory, Chem. Eng. Sci. 17, 149-154, 1962. Herlina and Jirka, G. H.: Application of LIF to investigate gas transfer near the air-water interface in a grid-stirred tank, Exp. Fluids, 37(3), 341–349, 2004. Herlina and Jirka, G. H.: Experiments on gas transfer at the air-water interface induced by oscillating grid turbulence, J. Fluid Mech. 594, 183–208, 2008. Ho, D. T., Law, C. S., Smith, M. J., Schlosser, P., Harvey, M., and Hill, P.: Measurements of air-sea gas exchange at high wind speeds in the Southern Ocean: Implications for global parameterizations, Geophys. Res. Lett., 33 L16611, doi:10.1029/2006GL026817, 2006. Jacobs, C., Kjeld, J. F., Nightingale, P., Upstill-Goddard, R., Larsen, S., and Oost, W.: Possible errors in CO2 air-sea transfer velocity from deliberate tracer releases and eddy covariance measurements due to near-surface concentration gradients, J. Geophys. Res.-Oceans 107 (L3128), doi:10.1029/2001JC000983, 2002. Jacobs, C. M. J., Kohsiek, W., and Oost, W. A.: Air-sea fluxes and transfer velocity of CO2 over the North Sea: results from ASGAMAGE, Tellus B, 51(3), 629–641, 1999. Jähne, B., Heinz, G., and Dietrich, W.: Measurement of the diffusion coefficients of sparingly soluble gases in water, J. Geophys. Res.-Oceans 92, 10 767–10 776, 1987. Jähne, B., Huber, W., Dutzi, A., Wais, T., and Ilmberger, J.: Wind/wave tunnel experiments on the Schmidt number and wave field dependence of air-water gas exchange, in: Gas Transfer at Water Surfaces, edited by: Brutsaert, W. and Jirka, G. H., Reidel, Dordrecht, 303–310, 1984. King, D. B. and Saltzman, E. S.: Measurement of the diffusion coefficient of sulfur hexafluoride in water, J. Geophys. Res.-Oceans, 100, 7083–7088, 1995. McGillis, W. R., Edson, J. B., Hare, J. E., and Fairall, C. W.: Direct covariance air-sea CO2 fluxes, J. Geophys. Res.-Oceans, 106(C8), 16 729–16 745, 2001a. McGillis, W. R., Edson, J. B., Ware, J. D., Dacey, J. W. H., Hare, J. E., Fairall, C. W., and Wanninkhof, R. Carbon dioxide flux techniques performed during GasEx-98, Mar. Chem., 75, 267–280, 2001b. McGillis, W. R., Edson, J. B., Zappa, C. J., Ware, J. D., McKenna, S. P., Terray, E. A., Hare, J. E., Fairall, C. W., Drennan, W., Donelan, M., DeGrandpre, M. D., Wanninkhof, R., and Feely, R. A.: Air-sea CO2 exchange in the equatorial Pacific, J. Geophys. Res.-Oceans, 109, 2004. McKenna, S. P. and McGillis, W. R.: The role of free-surface turbulence and surfactants in air-water gas transfer, Int. J. Heat Mass Trans., 47(3), 539–553, 2004. Münsterer, T. and Jähne, B.: LIF measurements of concentration profiles in the aqueous mass boundary layer, Exp. Fluids, 25, 190–196, 1998. Nightingale, P. D., Liss, P. S., and Schlosser, P.: Measurements of air-sea gas transfer during an open ocean algal bloom, Geophys. Res. Lett., 27(14), 2117–2120, 2000a. Nightingale, P. D., Malin, G., Law, C. S., Watson, A. J., Liss, P. S., Liddicoat, M. I., Boutin, J., and Upstill-Goddard, R. C.: In situ evaluation of air-sea gas exchange parameterizations using novel conservative and volatile tracers, Global Biogeochem. Cy., 14, 373–387, 2000b. Siddiqui, M. H. K., Loewen, M. R., Asher, W. E., and Jessup, A. T.: Coherent structures beneath wind waves and their influence on air-water gas transfer, J. Geophys. Res.-Oceans 109, C03024, doi:03010.01029/02002JC001559, 2004. Wanninkhof, R.: Relationship between wind speed and gas exchange over the ocean, J. Geophys. Res.-Oceans, 97, 7373–7382, 1992. Wanninkhof, R., Asher, W. E., Weppernig, R., Chen, H., Schlosser, P., Langdon, C., and Sambrotto, R.: Gas transfer experiment on Georges Bank using two volatile deliberate tracers, J. Geophys. Res.-Oceans, 98, 20 237–20 248, 1993. Wanninkhof, R., Hitchcock, G., Wiseman, W., Ortner, P., Asher, W., Ho, D., Schlosser, P., Dickson, M.-L., Anderson, M., Masserini, R., Fanning, K., and Zhang, J.-Z.: Gas exchange, dispersion, and biological productivity on the west Florida shelf: Results from a Lagrangian tracer study, Geophys. Res. Lett., 24, 1767–1770, 1997. Wanninkhof, R., Sullivan, K. F., and Top, Z. Air-sea gas transfer in the Southern Ocean, J. Geophys. Res.-Oceans, 109, C08S19, doi:10.1029/2003JC001767, 2004. Woodrow Jr., P. T., and Duke, S. R.: Laser-induced fluorescence studies of oxygen transfer across unsheared flat and wavy air-water interfaces, Ind. Eng. Chem. Res., 40, 1985–1995, 2001. Zappa, C. J., Asher, W. E., Jessup, A. T., Klinke, J., and Long, S. R.: Microbreaking and the enhancement of air-water gas transfer velocities, J. Geophys. Res.-Oceans, 109, C08S16, doi:10.1029/2003JC001897, 2004.