The Superadiabatic Surface Layer of the Ocean during Convection

Abstract

Clear identification of the relatively weak superadiabatic potential temperature gradient in the ocean surface layer during convection has been made with the help of intensive vertical profiling measurements at an open-ocean site. In the surface layer the superadiabatic gradient, with a mean value of ?1.8 ? 10?4 K m?1, was a consistent feature of the convective boundary layer persisting throughout each of six consecutive nights. In the well-mixed layer, below the surface layer, the observed potential temperature was nearly constant and turbulent kinetic energy (TKE) dissipation rate approximately balanced the production of TKE by the buoyancy flux through the sea surface. In the surface layer the TKE dissipation rate was systematically larger than the production of TKE predicted by wind stress and mixed-layer similarity scaling.