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Aloysius Koufang Lo

Abstract

The role of humidity in estimating marine surface layer stratification in terms of the ratio, R, of the humidity contribution to the total static stability is evaluated. A recent study of Geernaert and Larsen employs a system of simultaneous equations for calculating R. The present study requires only simple algebraic relations to arrive at the approximate solution of R. In the approximate solution, the value of R is explicitly represented in a single equation as a function of potential temperatures and the corresponding virtual potential temperatures. The exact solution of R is obtained directly using the Monin-Obukhov stability parameters with and without humidity effect. Static stability and transfer coefficients, as well as deposition velocity of SO2 over an air-sea interface, are calculated using the direct bulk aerodynamic method similar to that of Lo. Detailed study on characteristics of humidity effect on atmospheric stratification, especially for cases of large sea-air temperature differences under stable conditions, are presented. Implication of humidity effect on stability pertaining to the theory of “countergradient” phenomenon is also presented.

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Aloysius Kou-Fang Lo

Abstract

This study presents a method that can directly determine the boundary-layer fluxes of heat and momentum, as well as both extrapolated wind and temperature profiles to the surface of a water body. The only input information that is required is a single level of wind and temperature in addition to the water surface skin temperature. The present study features a method that enables one to determine boundary-layer flux parameters directly without having to resort to the use of tabulations or nomograms. Therefore, the present method can be a valuable tool in many practical applications especially for marine boundary layer studies using buoy data as input. In essence, the present method determines the Monin-Obukhov length directly from the bulk Richardson number instead of indirectly through nomograms or being considered as a known input. Thus, the present method is an improvement over the conventional bulk method. Results of the present study agree well with those that appear in the literature.

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