Carbon dioxide flux techniques performed during GasEx-98

A comprehensive study of air-sea interactions focused on improving the quan tification of CO2 fluxes and gas transfer velocities was performed within a large open ocean CO2 sink region in the North Atlantic. This study, GasEx- 98, included shipboard measurements of direct covariance CO2 fluxes, atmosp heric CO2 profiles, atmospheric DMS profiles, water column mass balances of CO2, and measurements of deliberate SF6-(3) He tracers, along with air-sea momentum, heat, and water vapor fluxes. The large air-sea differences in p artial pressure of CO2 caused by a springtime algal bloom provided high sig nals for accurate CO2 flux measurements. Measurements were performed over a wind speed range of 1-16 m s(-1) during the three-week process study. This first comparison between the novel air-side and more conventional water co lumn measurements of air-sea gas transfer show a general agreement between independent air-sea gas flux techniques. These new advances in open ocean a ir-sea gas flux measurements demonstrate the progress in the ability to qua ntify air-sea CO2 fluxes on short time scales. This capability will help im prove the understanding of processes controlling the air-sea fluxes, which in turn will improve our ability to make regional and global CO2 flux estim ates. (C) 2001 Elsevier Science B.V. All rights reserved.