GAS TRANSFER EXPERIMENT ON GEORGES BANK USING 2 VOLATILE DELIBERATE TRACERS

A gas exchange experiment was performed on Georges Bank using deliberate tracers sulfur hexafluoride (SF6) and helium 3(He-3). The concentrations of the tracers were measured in the water column over a period of 10 days. During this time the patch grew from an 8-km-long injection streak to an area of about 500 km2. The ps transfer velocity was determined from the change in the ratio of the tracers over time scaled to the ratio of their Schmidt numbers. A near-linear relationship between gas exchange and wind speed was observed based on four experimental points covering a wind speed range from 3 to 11 m/s. The results fall in the upper part of the range of gas transfer-wind speed relationships developed to date. Wind speeds during the experiment obtained from anemometers on the ship, on a free floating drifter, and on a fixed mooring showed significant differences. With the ability to measure gas transfer velocities over the ocean on timescales of several days, accurate wind speed/stress measurements are imperative to obtain a robust relationship between gas transfer and wind speed.