基于DEM的起伏地形下散射辐射计算方法研究

【作者】 韩磊；

【导师】 缪启龙； 邱新法；

【作者基本信息】 南京气象学院 ， 气象学， 2004， 硕士

【摘要】 本文结合现代空间信息技术，利用高分辨率的数字高程模型(Digital Elevation Model)，探讨了实际地形下散射辐射的计算方法问题。 本文的讨论主要着眼于三个方面： 1、散射辐射各向异性特点 利用环日假设理论，把太阳散射辐射分解为各向同性散射和环日散射两部分，并以水平地面上的直接辐射和散射辐射各自在总辐射中所占比例来表示其权重，描述实际散射辐射各向异性的特征。再对“可见”天穹积分，得到瞬时来自“可见”天穹的散射辐射总量。最后从日出到日没时间段进行积分，得到散射辐射日总量。 2、地形因子的影响 在对“可见”天穹积分时，对2π范围内各方向上的遮蔽状况进行判断，确定每个方向上由前方地势所造成的遮蔽角度，从而反映周围地形造成的遮蔽影响，实现对“可见天穹”的积分。 同时，与各向异性密切相关的要素：坡度、坡向和太阳位置都考虑在其中。计算结果表明：各向同性假设下散射辐射量的坡向差别甚小，仅与开阔度有关，随开阔度增大而增大，随坡度增大而减小；各向异性假设下，散射辐射南坡最大，向东、西方向对称减小，北坡最小；南坡散射辐射随坡度增加而增加；北坡随坡度增加而减小；散射辐射量随太阳季节变化显著，冬季太阳高度角小，地形影响较大；夏季太阳高度角大，地形影响小。 3、地理空间信息技术 在计算地形因子对散射辐射的影响时，利用了全国1km×1km分辨率的数字高程模型(DEM)，以栅格数据形式，在PCI geomatica软件支持下，计算每个格点的遮蔽状况及相关地形参数，结果表明，地形作用的表现效果良好。 总结本文的技术与方法，本文以各向同性与各向异性权重分离方法描述了散射辐射各向异性特征；以平地散射辐射与地形因子结合方式详细探讨了地形因子的作用;以DEM数据与现代地理信息软件相配合，尝试了高效的现代地理空间信息计算技术。最后，本文给出了计算的实际起伏地形下的散射辐射全国分布图。更多还原

【Abstract】 Attempt to calculate the diffuse irradiation on the actual terra by used of the modern geo-information technology and the high resolution Digital Elevation Model, we focused on 3 points in discussion:1. To construct an appropriate model to describe the anisotropic character of the diffuse-radiation. According to the circle-sun suppose, we decomposed it into 2 parts, one is the isotopic part and the other is anisotropic. A ratio allocates them. Then integral the whole visible vault of heaven to get the amount of diffuse radiation at one moment. Next, integral again from the sun-rise time to down, it is the one whole day diffuse radiation amount.2. Study the landform effects on the diffuse irradiation. When integralling the visible vault of heaven, it is necessary to estimate the shadow status on every direction in 2 circle. The slope and aspect are also effective. In isotropic model, the aspect is unimportant and the diffuse radiation is reducing with the slope’s increase. While the anisotropic model showed differently. The max diffuse irradiation is on the South aspect and the min on the North. On the South aspect, the diffuse radiation is increased with the slope’s going up while the North is reversed. In winter, the sun high is low, the landform effect seriously, while summer is opposition.3. The compute technology based on the high resolution DEM. We used 1km 1km DEM and PCI-geomatica software to deal with the multitudinous geo-information data, and evaluated every grid point landform shadow status. The results showed the landform well.In summaries, we use two parts, isotropic and anisotropic, to describe the anisotropic diffuse-radiation; Connected the horizontal diffuse-radiation and the land modulus to calculate the diffuse irradiation on actual terra; And modem geo-tech, DEM and PCI-geomatica software and so on, is convenient and helpful to deal withmass geo-data and geo-information.At the end of the paper, the distributing map of anisotropic diffuse-radiation on actual terra in China area are given.更多还原