Distributed Modeling of Global Solar Radiation over Rugged Terrain of the Yellow River Basin

Abstract

In rugged terrain,the global solar radiation(GSR) reaching on the surface is composed of three parts,i.e.direct solar radiation,diffuse solar radiation and terrain reflected solar radiation.The theories of these three kinds of solar radiation are different.Respective models are established which necessarily take integrated consideration of astronomical and geographic factors,local topographic factors(i.e.slope,aspect and terrain inter-shielding effect) and atmospheric physics factors are needed.Based on DEM(Digital Elevation Model) data and remote sensing data,a distributed model for calculating GSR over rugged terrain is developed,with routine meteorological observations as input.This model takes all consideration of factors influencing GSR.Using the established model,normals of annual GSR quantity with resolution of 1 km×1 km for the Yellow river basin was generated.Results suggest that influenced by local topographic factors,i.e.azimuth,slope and terrain inter-shielding effect,annual GSR quantity over mountainous areas is smaller than that over plains generally.The influences of local topographic factors on GSR are changing with seasons and are more obvious in seasons that have a lower solar elevation angle.