Spatial and temporal patterns of solar radiation based on topography and air temperature
2002
Kang, S. | Kim, S. | Lee, D.
Incident solar radiation is a driving force for many ecological and hydrological processes. For this study, we developed TopoRad, a new radiation model, to describe spatial and temporal patterns of daily radiation based on topography and daily temperature regimes. The model was applied to the Mount Jumbong Forest, located in the mid-eastern area of the Korean peninsula; and the model calculations were evaluated by varying the spatial scales of the digital elevation models (DEMs). In the TopoRad, a clearness index was used to calculate global radiation on a horizontal surface and to partition direct and diffuse radiation. Topographic corrections were separately calculated for each direct and diffuse radiation, using daily topographic modifiers calculated from a DEM. TopoRad predicted daily global radiation of five weather stations with a mean absolute error of 3.1 MJ m(-2) day(-1) and a mean bias of -0.3 MJ m(-2) day(-1). In the spatial application for Mount Jumbong Forest, distinctively different patterns between direct and diffuse radiations were found where direct radiation (5.2 MJ m(-2) day(-1)) had more influence than diffuse radiation (4.6 MJ m(-2) day(-1)) on annual mean daily radiation. When the scaling effect was inspected across different spatial resolutions, the predicted global radiation was nonlinearly related to spatial resolutions. As the spatial resolution became more coarse, the predicted radiation decreased for south-facing slopes and increased for north-facing slopes, indicating that the predictions from the models cannot be generalized for gradients. TopoRad is better suited to predict daily radiation in rugged landscapes where fine-scale prediction is required.
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