Abstract
For the evaluation of vertical turbule n t fluxes over wide areas such as oceans, it is difficult to measure three dimensional turbulent fluctuations, mean vertical profiles of wind speed, potential air temperature and humidity over the whole area in question.
Accordingly, for practical purposes a simple and more convenient evaluat i ng method should be developed.
In this paper, such a method is developed by use of flux-profile relationship.
For obtaining solutions, simultaneous transcendental equations ar e solved by an iterative method. The following properties of turbulent fluxes are studied in this paper:
(1) Estimation of mean roughness height by our bulk method shows good agreem e nt with the one by the extrapolation method of lower profiles of mean wind velocities under the best neutral condition. And also it is found that there exists an optimum choice of measurement levels to make errors of estimated Z0 minimum.
(2) The fluxes of sensible heat and momentum a gree relatively well with the ones obtained by direct measurement, but as latent heat fluxes become larger, the values obtained by the bulk method tend to be larger than the directly measured ones.
(3) The fluxes of momentum, sensible heat and latent heat obtained by our bulk method over the sea agree very well with ones obtained by Kondo's bulk formulae.
(4) Diurnal variation of sensible heat flux obtained by our method sh o ws good correspondence with that of net radiation and cloud amounts.
(5) Momentum fluxes calculated by our bul k method vary a little with the two measurement levels except under stable condition. And relative errors of estimated fluxes to the directly measured average fluxes are 30% to 50% about in the middle levels of profiles, except near neutral condition. On the other hand, the variations of sensible heat fluxes with the two measurement levels are relatively small under diabetic condition and relative errors of them are also minimum in the middle of profiles.
