Computations of oxygen fluxes through the sea surface and the net production of organic matter with application to the Baltic and adjacent seas

Abstract

The transfer F ot of oxygen between the ocean and the atmosphere is computed from the formula F ot = V [O 2 − (1 + x)O 2 s] where V is the transfer velocity, O 2 the actual oxygen concentration of the surface water, O 2 s the saturation concentration, and x a factor that takes into account the effect of gas transfer due to bubbles. Monthly mean oxygen fluxes were calculated from the formula with historical hydrographical data. By adjusting the value of x , the formula was tuned to obtain a vanishing net annual oxygen flux through the sea surface in the Baltic proper. This occurs when x equals 0.025. Bubble‐driven gas transfer thus tends to supersaturate surface water. The gas transfer formula is tested by a comparison between published estimates of the net production of organic matter in the photic layer and estimates obtained with computed oxygen fluxes through the sea surface. The test indicates that the formula is reliable. The test further shows that it is possible to compute the net production of organic matter in the photic zone, using the formula for oxygen exchange presented here, and salinity, temperature, and oxygen data from the surface layer.