应用SUNLIGHT模型求算微起伏区太阳辐射值——以松嫩平原大安古河道区为例

CALCULATION OF SOLAR RADIATION USING SUNLIGHT MODEL IN SLIGHT RELIEF REGION-Taking Da' an Paleochannel Region of Songnen Plain as an Example

SUNLIGHT模型充分考虑了地形要素对太阳辐射的影响,适用于计算小流域的太阳辐射并较精确地描述其在微起伏区的分布特性.利用SUNLIGHT模型,对松嫩平原大安古河道区太阳辐射的直射辐射和散射辐射进行了计算,并对该古河道区的太阳辐射能的分布作出精确的描述,为土地潜力性评价提供基础.

Solar radiation is the ultimate energy source for ecosystems and the base for all ecological processes. The radiation in the relief area will be obviously affected by the terrain. SUNLIGHT model takes such topographic effect into account in detail and can be used to calculate the solar radiation including direct, diffusive and reflective radiation of each point within a watershed scale. The model first calculates the topographic parameters such as slope, azimuth, view factor and sheltering angle of each point in a watershed based on DEM, then decides the sun rising and sun setting time angles of each point by comparing the angles calcualted from sun orbital equations for any slope and aspect and the sheltering angle in the sun rising and sun setting direction. The direct solar radiation can be calculated after getting the actual sun rising and setting angles of each point. The diffusive and reflective radiation can be simply calculated by using topobraphic parameters and actual survey data of a flat area site without topographic effect.Da'an paleochannel region is a newly found paleochannel in the Songnen Plain. It is the current most promising barren area that can be reclaimed. The paper applies the SUNLIGHT model in this region to know the detail spatial distribution of solar radiation. The results show that the possible direct radiation on May 15, 1994 was about 8.483 MG/m2 with normal deviation of 2.041 MJ/m2. Though the radiation distributes more evenly than in other relief area, it will be changed sharply in the slope area. The regression function between the direct solar radiation and topographic parameters can be represented as:Sdr = 0.002H- 3.435α + 0.029β + 20.498VF - 11.71(R - 0.41)where H,α, β and VF represent altitude, slope, azimuth and view factor respectively. And PCA analysis shows the most important topographic factors that affect direct solar radiation in this area are view factor and slope. Their correlative coefficients with the first axis are 0. 332 and - 0. 29 respectively. The results of the model have indicted that it can give a precise calculation for the distribution of solar radiation and thus provide the background for further study.