Abstract
When the water layer with a salinity gradient positive downwards undergoes the surface cooling, the development of thermosolutal convection can be investigated by a simple model, in which diffusivities are given by the effective thermosolutal Rayleigh number. Results showed; (1) the appearance of a series of convecting layers separated by non-convecting thin sheets : step-like structures of temperature and salinity profiles are formed; (2) the uppermost convecting layer extends downwards and the approximate uniformity of temperature and salinity is attained in a relatively short time; (3) the density difference between adjacent convecting layers increases with time; (4) even if the initial stratification is very stable because of the temperature gradient positive upwards, the convection develops rather rapidly due to the surface cooling; (5) magnitudes of apparent diffusivities are in the range of 10-2 to 1 cm2 s-1.
