GEOGRAPHICAL RESEARCH ›› 2014, Vol. 33 ›› Issue (7): 1297-1305.doi: 10.11821/dlyj201407010

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Surface modeling of sunshine percentage in China based on a modified version of HASM

ZHAO Na1,2, YUE Tianxiang1, ZHAO Mingwei1,2   

  1. 1. Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China;
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2013-11-12 Revised:2014-04-22 Online:2014-07-10 Published:2014-07-10

Abstract: Sunshine percentage is one of the important factors that influences the computation of sunshine hour and solar radiation. The computational results of sunshine percentage will undoubtedly affect the relevant researches. In order to solve the error problem that had long troubled the interpolation method, Yue developed a novel surface modeling method, High Accuracy Surface Modeling (HASM), based on the fundamental theorem of surfaces which makes sure that a surface is uniquely defined by the first and the second fundamental coefficients of it. Numerical tests have shown that HASM is much more accurate than the classical methods such as kriging, Inverse Distance Weighted (IDW) method, and spline. Surface modeling of Digital Elevation Model (DEM), ecosystem change and soil properties also indicate that HASM has increased interpolation accuracy. Despite its popularity, however, a common phenomenon is found that the result of HASM is not optimal since the theoretical basis of it is not complete. To improve HASM's simulation skills in interpolating sunshine percentage in China, this research gives a modification of HASM, namely HASM.MOD, which introduces the mixed partial derivative term, considers the local details of the surface and is theoretically perfect. The introduction of the mixed partial derivative term in HASM.MOD reflects the local warping of the surface, namely its deviation from tangent plane at the point under consideration. We then use Gauss synthetic surface to validate the performance of HASM.MOD and HASM. HASM.MOD is then used to simulate the monthly mean sunshine percentage by using observed data from 752 stations for the considered period (1950-2010). We also compare the performance of HASM.MOD with those of HASM and other interpolators: kriging and inverse distance method (IDW). Numerical tests and real world studies show that the simulation accuracy of HASM. MOD is higher than that of other methods in this study. As the basic geographical data, the sunshine percentage produced by HASM.MOD can provide support for other applications.

Key words: HASM, sunshine percentage, interpolation, accuracy, China