基于DEM的山地日照时数模拟时空特点及应用--以北京西山门头沟区为例

本文建立了一种基于数字高程模型（DEM）的山地日照时数模拟方法，并以北京西山门头沟区为例进行各月15日日照时数模拟与验证分析。结果表明，该区两个气象站的模拟值与实测值都具有较好的一致性（R^2=0.9772、0.9469）；在此基础上得到该区日照时数的分布时空变化特点：在时间上，夏季最多，春秋相当，冬季最少，全区冬季的变异比夏季更为显著；在空间上，不同地貌条件下阴阳坡的日照时数表现出显著差异。该方法避免了图解法中遮蔽图获取的大量野外测量工作和克服了经验方程依赖站点数目以及它和解析法对地形遮蔽欠考虑的缺陷，但该方法需要有一定精度的DEM支持。该方法能较为准确和定量地反映山地日照时数时空分布规律，因此在山地资源可持续利用和生态环境恢复建设中具有较强的理论与实践意义。

Sunshine Hours Modeling and Spa-temporal Variation Analysis Based on DEM in Mountainous Area--Take Mentougou mountain in west Beijing as the example

Sunshine hours is an important meteorological and ecological indicator.To understand its complex spa temporal distribution and variation in mountainous area is essential in the mountain research and development.We proposed an area based model to estimate daily amounts of sunshine hours based on Digital Elevation Model and the process of sunlight transmission.and took Beijing West Mountain Mentougou district as the example,modeled the monthly distribution of sunshine hours and analyzed the characteristics of its spa temporal variation.The results demonstrated that the derived values agreed well with the observed values of the two meteorological stations in study area,with R 2 =0.9722 and 0.9649 respectively.The temporal variation of sunshine hours was strong,with the average value of 14.41 h in July,10.54 h in March but 6.34 h in December,and characterized by: much in summer,less in winter and moderate in spring and fall. On the contrary,the standard deviation (SD) was much in winter but less in summer ,i.e.,2.33 in December,1.24 in March but 0.33 in July ,which meant that the spatial variation of sunshine hlurs in winter was stronger than other seasons.Then took the sunshine hours of midwinter day as the example and analyzed the characteristics of its distribution in spatial. The results demonstrated that the sunshine hours of units with different slope, aspec tand geomorphologic type had notable variation from 3.38 h to 8.87 h. It was suggested that this method could calculate the sunshine hours of different tine and space in various slope,aspect,geomorphology and shading condition.So it is important in the understanding of the sunshine hours' spa temporal distribution and variation of tilted surfaces,and in the research and application of land resources evaluation,natural conservation area planning,ecological process research and other related study subjects in mountainous area.