Model-validated parametrization for air-sea gas transfer in the north Indian Ocean

Mixed-layer CFC-11 saturations measured in the northwestern Indian Ocean during the 1995 World Ocean Circulation Experiment (WOCE) along 17N are compared to those from a numerical model using three alternative parametrizations for the air-sea flux of CFC-11. The Wanninkhof [1992] gas flux parametrization for climatological winds gives gas saturations which agree best with those observed. The observed and model mixed-layers are in equilibrium with the contemporary atmosphere to within 1% (the experimental error) in the summer of 1995, excluding cold coastal upwelled waters. When the model is used to extend the space and time scales of the observations in the Arabian Sea, widespread supersaturations of 5% due to weak winds and warming are predicted in the spring and fall, and undersaturations of 5% due to mixing in the winter. The model validation of CFC-11 transfer parametrization and investigation of temporal and spatial variability in saturation are applicable to the physically-forced saturation variations of carbon dioxide and other gases of interest.