贵州高原起伏地形下日照时间的时空分布

The Spatial and Temporal Distribution of Insolation Duration over Rugged Terrains in the Guizhou Plateau

由于坡度、坡向和地形之间相互遮蔽等局地地形因子的影响，实际起伏地形下的日照时间与水平面上的日照时间有一定差异。该文建立了一种基于数字高程模型（DEM）的起伏地形下日照时间的模拟方法，计算了起伏地形下贵州高原100m×100m分辨率日照时间的时空分布。结果表明：坡度、坡向、地形遮蔽对日照时间的影响较大，实际起伏地形下日照时间的空间分布具有明显地域特征。1月太阳高度角较低，坡度、坡向的作用非常明显，地形遮蔽面积较大，日照时间的空间差异较多，日照时间为16～142h，最大值约为最小值9倍；7月太阳高度角较高，地形遮蔽面积相对较小，日照时间的空间差异相对较少，日照时间为133～210h，最大值为最小值1．6倍，但由于7月日照时间相对较多，局地地形对日照时间影响仍明显。4月、10月日照时间及其变化幅度介于1月和7月之间。

Due to local terrain factors such as slope, aspect and terrain inter-shielding, the insolation duration over rugged terrain is different from over horizontal surface. Calculating the insolation duration over rugged terrain is very difficult. In the mountainous regions of complicated landform and great height difference, the observation data of the existing weather stations are far from enough to reflect the spatial distribution of the complicated sunshine time. Guizhou Province, which is from 24°37′N to 29°13′N and from 103°36′E to 109°35′E, lies in the plateaus and mountains in the western China. The physiognomy of the whole Province fails roughly into the categories of plateaus, mountains, hilly land, and basins. 92.5 % of the total land area is mountains and hilly land. Based on Digital Elevation Model （DEM） and Geographical Information System （GIS）, the distributed models for calculating insolation duration over rugged terrain are developed. Applying the models to Guizhou Plateau with 100 m × 100 m DEM data, the elaborated spatial distributions of insolation duration over rugged terrain are generated. The insolation duration over rugged terrain of considering slope, aspect and terrain inter-shielding is analyzed. The influences of slope, aspect and the terrain inter-shielding on sunshine duration are very big. The spatial distribution of sunshine duration has apparent terrain feature over rugged terrain. The solar altitude angle is quite low in January; the effect of slope, aspect is very apparent. The shadow areas of topography are relative large and the spatial difference of sunshine time is big. The insolation duration varies spatially from 16 to 142 hours, and the maximum is about 9 times as the minimum. The solar altitude angle is quite high in July; the shadow areas of topography are relative small. The insolation duration varies spatially from 133 to 210 hours, and the maximum is about 1,6 times as the minimum. But the sunshine time over horizontal surface is much in July, and the influence of local terrain on the insolation duration is still obvious. The insolation duration and its amplitude of variation vary between in January ,July and in April, October. The annual average insolation duration varies spatially from 768 to 1824 hours, and the maximum one is about 2.4 times as the minimum one. The effect of slope, aspect and the terrain inter-shielding on annual sunshine duration is quite great. The spatial difference of it is very evident. Therefore, the effect of complex topography on insolation duration should be considered.