Measurements of Gas Concentration Fluctuations at Water Surface

Experiments in a grid‐stirred laboratory tank $(0.5m\times 0.5m\times 0.4m)$ have been conducted in an effort to elucidate the details of the surface transfer mechanisms, including the structure of up‐ or down‐welling motions and existence of various boundary layers. In addition to earlier two‐component measurements of the turbulent near‐surface velocity field, a gas microprobe has been constructed and used for measurements of gas fluctuations. The gas probe uses the polarographic principle for the measurement of oxygen and has tip dimensions of the order of a few microns. Measurements are presented that display the conditions in the gas boundary layer (about 400‐microns thickness), including mean and fluctuating conditions.