EVALUATION OF TURBULENT FLUXES AT THE OCEAN SURFACE USING SURFACE RENEWAL THEORY

An internally consistent model is presented that can be used to determ ine the ocean surface fluxes of heat, moisture, and momentum, given bu lk sea surface temperature and atmospheric temperature, humidity, and winds measured at a single level within the atmospheric surface layer. This model is based upon surface renewal theory as described by Bruts aert [1975a]. Liu et al. [1979] (hereinafter referred to as LKB) made partial use of this theory, and further improvements to the LKB parame terization have been made by Fairall et al. [1996a]. The present model includes the following improvements relative to the LKB and Fairall e t al. bulk flux models: incorporation of a new time-scale parameteriza tion for surface renewal, inclusion of capillary waves in the surface roughness model, derivation of the surface roughness scales of water v apor and heat based solely upon surface renewal theory; and incorporat ion of a new surface skin temperature model. The model is validated us ing shipborne observations of surface fluxes and surface meteorology t hat were obtained in the central Pacific Ocean, the western tropical P acific, the subtropical Pacific, and the midlatitude North Atlantic. C omparisons of model results with covariance fluxes of latent heat show biases of less than 3% for all locations, with little dependence of e rror on wind speed; similar results are obtained for sensible heat and momentum flux. An assessment is given of the advantages of the presen t scheme over the LKB and Fairall et al. schemes. The model results ar e interpreted in the context of the physical processes involved in det ermining the surface roughness length and the surface renewal timescal e.