在广泛总结前人研究的基础上,提出了一个改进的、基于DEM数据的、起伏地形条件下的日照时间计算模型,在以往计算模型的基础上引入地球曲率修正因子Q,提高了模型的计算精度。并在此基础上,计算了全国6个典型地貌类型区,在春秋分日、夏至日和冬至日,两个空间分辨率下(500m和1km)地面日照时间的空间分布。应用数理统计、数学模拟和比较分析的研究方法,对模型修正前后计算所得的地面日照时间数据进行了对比分析,并对所得地面日照时间从不同地貌类型和不同空间尺度两个方面进行了地形与空间尺度效应研究。阐明了区域日照时间随地形地貌和空间分辨率变化的规律,对应用中计算地面日照时间的DEM空间分辨率选择具有指导意义。

A sunlit time computation model based on the DEM data in rough terrain is developed in this paper. In order to improve the accuracy of the calculation, an earth curvature adjusting factor Q is carried out in the model based on the former researchers. In this study, 6 typical terrain areas within China were selected and their spatial distributions of sunlit time on the vernal and autumnal equinoxes, the Summer Solstice and midwinter day in two different resolutions (500m and 1km) were calculated using the developed model. The sunlit times calculated by the revised models were compared with the previous models. And the topographic and spatial-scaling effects on the sunlit time were analyzed through two aspects: the different terrain types and different spatial scales of the original DEM data. The changing rules of sunlit time according to the geomorphology and spatial scale were found out, which are very significative in applications.