ABSTRACT
A hierarchy of thermal, salt, and viscous boundary layers can be distinguished owing to the specific conditions and processes of heat, mass, and impulse exchange between the ocean and the atmosphere near the interface [58]. The primary boundary layers in the water in this hierarchy, which we intend to consider here, are very close to the surface and are the thinnest ones. Molecular processes (heat conductivity, diffusion, viscosity) play a dominant role in their dynamics, as a result of which they concentrate the maximum vertical gradients of temperature, salinity, velocity, and many other characteristics. In principle, the entire sphere discussed below is more often called a viscous molecular sublayer. As our attention will be concentrated mainly on its thermal structure, we will consider the part of the sublayer where the maximum vertical temperature gradients are concentrated as a 'thermal boundary layer'. The expression 'salt boundary layer' will be used in the same sense but as applied to salinity. This approach is justified the more so as the stated boundary layers should have a different thickness inside a viscous molecular sublayer owing to the different coefficients of heat conductivity and diffusion. Comprehension of the regularities of the behaviour and formation of the thermal boundary layer structure is of paramount importance when investigating the characteristics of the nearsurface layer of the ocean.
