Laboratory Experiments on CO 2 Gas Exchange with Wave Breaking.

The CO2 gas transfer velocity ( K CO 2 ) at air–sea interface is usually parameterized with the wind speed, but to a great extent it is defined by waves and wave breaking. To investigate the direct relationship between K CO 2 and waves, laboratory experiments are conducted in a wind-wave flume. Three types of waves are forced in the flume: modulational wave trains generated by a wave maker, wind waves with 10-m wind speed ranging from 4.5 to 15.5 m s−1, and (mechanically generated) modulational wave trains coupled with superimposed wind force. The wave height and wave orbital velocity are found to be well correlated with K CO 2 whereas wind speed alone cannot adequately describe K CO 2 . To reconcile the measurements, nondimensional equations are established in which gas transfer velocity is expressed as a main function of wave parameters and an additional secondary factor to account for influence of the wind. [ABSTRACT FROM AUTHOR]