1. 3.3 Gas exchange Turbulent vertical motions in both the atmosphere and ocean are strongly suppressed near the air-sea interface.  STAGNANT FILM MODEL = 2 stable stagnant films of finite thickness in atmosphere and ocean, respectively, through which gases can diffuse only by molecular diffusivity 

2. 3.3 Gas exchange For atmosphere layer: For ocean layer: Without any sources or sinks in the stagnant film:

3. 3.3 Gas exchange k a /S a ~> 1000 cm/hr k w ~= 10 cm/hr  Ignore the atmosphere stagnant film K g = k w /S a

4. 3.3 Gas exchange Measurements and theory indicate that the gas exchange coefficient is controlled by the level of turbulence near the interface, primarily controlled by the boundary wind stress and by the Schmidt number (Sc = /  ) Additional processes: Type of wave Breaking waves and formation of air bubbles Temp and humidity gradients n =1 for stagnant film model, but there are other models