This award supports Dr. Rik Wanninkhof of Lamont-Doherty Geological Observatory to collaborate with Dr. Bernd Jaehne of the Institute of Environmental Physics of the University of Heidelberg in a study of the influence of waves on gas exchange at the air - water interface. The initial phase of the research will be performed in an unusually large wind-wave tunnel in Delft, Holland; its great size will permit generation of high wind speeds and breaking waves. Drs. Wanninkhof and Jaehne will capitalize on an opportunity to add their experiments to an ongoing Dutch research program, VIERS, which was originally designed simply to study the effect of waves on the backscatter signal of radar beams directed at the water surface. Dr. Jaehne will measure heat and gas fluxes across the interface using 3He and 4He. Dr. Wanninkhof will perform gas exchange measurements of several compounds of biogeochemical significance: methane, carbon dioxide and nitrous oxide, plus sulfur hexafluoride (a tracer gas). The Dutch groups are obtaining extensive physical data on wave form, surface tension, water viscosity, etc., which are necessary complements to the gas exchange measurements. Much effort has been put into quantifying the relationship between gas exchange and wind speed, since it is expected that a disproportionate amount of gas flux occurs in high wind conditions, where, for example, breaking waves are generated. The exchange of gases between the ocean and the atmosphere is still poorly understood due to the difficulty of measuring the process in the field in anything but very calm water. This collaborative project is the first time that surface water turbulence, which regulates the rate of gas exchange, will be well characterized at the same time that gas exchange measurements are made in a wind driven system.
