Study on fluxes of momentum and sensible heat, the drag coefficientC _d and roughnessZ ^*₀

Abstract

In this paper, fluxes of momentum and sensible heat are discussed with the data collected by tethered balloon sounding system over the Philippine Sea during the cruise of the R/VSCIENCE 1 from September through October in 1987. These fluxes were calculated using the semempirical flux-profile relationships of Monin-Obkhov similarity theory with observed data. The friction velocityU. was determined by the observed data's least-square fit with the similarity formulae under stable, neutral and unstable conditions. The roughnessZ ₀ was determined byZ ₀=a₁ (U_*/g), then substituted into the similarity formulae to computeU _* again. The final values ofU _* andZ ₀ could be determined through this iteration. The flux temperatureθ _* was calculated from the temperature profile withZ ₀ determined above. Finally the fluxes of momentum and sensible heat, and the drag coefficientC _D were obtained by computation withU _* θ _* and the wind speed (U ₁₀) at 10 meters above the sea surface.