Abstract
The Bowen ratio energy balance method is one of the most popular methods to estimate latent and sensible heat fluxes from lands. Usually, the temperature and water vapor pressure to calculate the Bowen ratio can not be measured so accurately. Therefore, the estimated values of latent or sensible heat fluxes sometimes do not agree with each other when measurement heights differ. In order to improve the accuracy of estimation, the temperature and water vapor pressure profiles are often smoothed by fitting empirical equations.
In this paper, the necessary condition, which satisfies the assumption that the Bowen ratio is constant in the surface sublayer, to fit the profiles over rough surface into equations is clarified in the Bowen ratio energy balance method. The empirical equation which satisfies such a condition should be used. If the profiles are fitted under this condition with experimental data measured over a paddy field, the estimated latent heat flux or sensible heat flux almost completely agrees with each other using any temperature and water vapor pressure at two different heights. Since the above assumption is not always satisfied when the Bowen ratio is calculated with measurement values, the values of the Bowen ratio are sometimes different depending upon measurement heights.
