Analysis of Impact of Terrain Factors on Landscape-scale Solar Radiation

Abstract

Incident solar radiation is one of the major sources of energy for driving biological and physical processes on earth. In this paper, simple conversion factors are designed to determine how the four landforms (i.e. plain, plateau, hill and mountain) will affect incident solar radiation at one month intervals using the ArcGIS tool appropriate for regional solar radiation analysis. A comparison is made between simulation results and those measurements taken in actual radiation stations, providing a correlation R 2 of 0.9063. Results indicate first, that if the ratio of the monthly mean of the DEM-based regional solar radiation to the monthly mean of the hypothesis DEM-based regional solar radiation is defined as the conversion factor (R) of the solar radiation and the ArcGIS tool for regional solar radiation analysis is employed, then the computation can be simplified and the impact of terrain factors on incident solar radiation can be correctly represented. Secondly, with each of the four landforms, R varies according to the season, slope gradient and aspect; the season induces more impacts than the terrain factors; R increases first and then decreases when the aspect changes clockwise, but decreases continuously with an increase in slope grade; R varies in a complex way in the case of mountains, especially for grade-five slopes. Thirdly, R increases initially and then decreases in a sinusoidal manner with an increase in aspect under the influence of slope gradient during the winter; R varies in a linear and somewhat symmetric manner (monotone increasing, monotone decreasing and stable) with the increase in slope gradient and under the influence of the aspect. These results are helpful in studying the impact of terrain factors of different landforms on incident solar radiation on the landscape scale using the simple conversion factors.