Abstract
The heat budget at water surface is composed of short- and long-wave radiations and latent- and sensible-heats. In this paper we improved the estimation of short- and long-wave radiations that have major effects on the water temperature change in a reservoir by analyzing observed radiation data at Tono Reservoir and simulating water temperature in the reservoir. The results are summarized as follows: 1) we can improve short-wave albedo by an equation that takes solar zenith angle, wind speed, humidity and scattered light ratio as parameters, 2) downward long-wave radiation estimation can be improved by considering not only cloudiness but also air temperature and proper emissivity, 3) the observed emissivity for upward long-wave radiation was 0.99 and 4) the accuracy of the downward long-wave radiation has more effect for improving water temperature estimation in a reservoir than short-wave albedo.
