INFLUENCE OF NON-BOUSSINESQ EFFECTS ON PATTERNS IN SALT-FINGER CONVECTION

The influence of non-Boussinesq effects on the quadratic coefficient o f the amplitude equations for patterns that are doubly periodic with r espect to the hexagonal lattice is discussed. The vertical length scal e is assumed to be long compared with the horizontal. Within this appr oximation, we consider a variety of non-Boussinesq effects including t he dependence of the fluid properties on temperature and salinity and the nonlinearity of the basic temperature and salinity profiles. We in clude some numerical calculations for the latter case. Oceanic data sh ow a pronounced nonlinearity of the basic temperature profile. Our cal culations, however, show this effect to be small, and, moreover, the d ominant contribution in this case is not covered by our asymptotic ''t hin finger'' analysis. The reasons for this are discussed. A nonlinear salinity profile, on the other hand, produces a much stronger effect, and our analysis seems to be applicable to this case.