A note on the analogy between momentum transfer across a rough solid surface and the air-sea interface

The aerodynamic classification of the resistance laws above solid surfaces is based on the use of a so-called Reynolds roughness number Re sub(s) = h sub(s)u sub(*)/v, where h sub(s) is the effective roughness height, v - viscosity, u sub(*) - friction velocity. The recent experimental studies reported by Toba and Ebuchi (1991), demonstrated that the observed "variability" of the sea roughness cannot be explained only on the basis of the classification of aerodynamic conditions of the sea surface proposed by Kitaigorodskii and Volkov (1965) and Kitaigorodskii (1968) even though the latter approach gains some support from recent experimental studies. In this paper, an attempt is made to explain some of the recently observed features of the "variability" of surface roughness. The "fluctuating" regime of the sea surface roughness is also described. It is shown that the contribution from the dissipation subrange to the variability of the sea surface can be very important and by itself can explain Charnock's (1955) regime.