Spatial distribution of incoming potential solar radiation based on solar analyst model and DEM in Xinjiang, China

Abstract

Incoming solar radiation is the primary driver for physical and biological process in the earth. Human activities, such as agriculture, forestry, land management, etc, ultimately depend on solar radiation. At a global scale, the geometry of earth's rotation and revolution about the sun cause the gradients of solar radiation. But topography is the major factor modifying the distribution of solar radiation at a landscape scale. Spatial solar radiation models provide a cost-efficient means for understanding the spatial variation of solar radiation over landscape scales. Geographic Information system (GIS) has become established tools for analyzing such models. Among such models, the Solar Analyst draws from the strengths of both point-specific and area-based models. It can calculate solar radiation integrated for any time period. In this paper, this model was used to estimate the spatial distribution of incoming potential solar radiation in Xinjiang, China. The 1km resolution digital elevation model (DEM) derived from 1:250000-scale topographic maps and other topographic factors (altitude, slope, aspect, etc derived from DEM) of Xinjiang were used as the basis for generating digital maps of the important parameter required to run Solar Analyst model. With the assistant of topographic factors and Solar Analyst model, the spatial distribution of monthly incoming potential solar radiation with 1km resolution was estimated. Actual solar radiation data were obtained from 13 meteorological stations for the result validation. Validation determined that the mean relative error (MRE) of incoming potential solar radiation ranges from 3.8% in Jul to 12.2% in Dec and the mean value of monthly MRE is 7.1%. The MRE is larger in winter than in other season. In conclusion, the simulated results of model are basically up to the level of application requirement. The Solar Analyst model may serves as a good tool for estimating spatial patters of monthly incoming potential solar radiation in Xinjiang. Application of Solar Analyst in Xinjiang and analysis of the spatial distribution characteristics of monthly incoming potential solar radiation have great significance for the research fields of agriculture, forestry and ecology in Xinjiang, China.