Measurements of the air-sea gas transfer and its mechanisms by active and passive thermography

In order to reliably measure air-sea gas transfer velocities in the field with a high spatial and temporal resolution a new technique has been developed called the controlled flux technique, CFT. The current implementation splits up into two independent techniques using active and passive thermography, respectively. The CFT field instrument has been successfully used during two research cruises along the California Pacific coast (MBL/CoOP, 1995) and on the North Atlantic (CoOP, 1997). In addition to in-situ gas transfer rates, thermography of the ocean surface gives direct insight into the mechanisms of gas transfer. It has been shown that surface renewal dominates the transfer processes even at low wind speeds.