Oxygen-deficient water mass on the bottom formed during period of stratification are broken down quickly by convection due to atmospheric temperature falling in abay. The quantitative study on convection has not been reported so far. Here we presented a one-dimensional model for quantifying convection due to surface cooling, and the results calculated by the model corresponded to both K. B. Katsaros's experimental values and ours pretty, such as the vertical distribution of temperature in the surface thermal boundary layer and the heat flux through surface, when the diffusion coeffcient for the model is given as half of that of water. Moreover by this model, the sinking value of the convection at surface layer can be estimated that which usually did not succeed in former methods, and the sinking flux of the convection due to the water temperature difference of 1-3° between surface and bottom, this time, is equal to the mass transfer coefficient due to the velocity of the wind of 3-5 m/s.
