Abstract
A model for estimating solar radiation taking account of shielding (shading) effect according to the surrounding topographic features was developed in order to perform the micrometeorological, numerical simulation over complicated topographical features. In this model, solar radiation is separated into a direct radiation component and a scattered radiation component, and the effect of topographic shielding by the direct radiation component was studied at a 50m grid interval. The model for estimating solar radiation was applied to the complicated topographical features, including the Kyoto Basin and the Tango Heights. The calculated values were compared with the observed data at the AMeDAS points of Kyoto, Miyama, Sonobe, and Nose. As a result, it was confirmed that the duration of solar radiation per day was shortened by at least 2 hours at the maximum due to the shading effect over the complicated topographical features. Also, this model was introduced into a three-dimensional atmospheric environmental simulator, and numerical simulation for micrometeorology. By incorporating the shading effect, the distribution of the solar radiation during wintry season (mid-December) during which the shading effect tends is remarkable because of the low solar altitude can be reproduced in detail. In fact, a daily accumulative solar radiation within the calculated region was in the range of 5.7-10.4 MJ/m2/day, showing unevenness due to the shading effect. The topographical shading effect decreased the temperature near the ground by 2.7K and increased the wind velocity from mountains to plains by 0.9 m/s at maximum.
