宁南地区地表特征参数及辐射平衡区域分布

Study on regional distribution of land surface parameters and components of surface radiation balance over South Ningxia

本文利用2001年6月30日LANDSAT-7 ETM+卫星遥感资料和宁夏南部及周边区域22个气象站气象观测资料,求得地表特征参数中NDVI、地表反射率、地表温度和地表辐射平衡各量中地表短波吸收辐射、地表长波辐射区域、大气逆辐射、净辐射的区域分布和分布直方图,将地表分成5类,分类别讨论了其各量分布特征。主要研究结果表明:地表特征参数及地表辐射平衡各量的分布均呈现明显的地带性,各区域分布图上山体、水体的轮廓很显著,主要原因是山上及河流附近生长着茂密的植被,说明植被的分布在相当程度上影响了辐射平衡各量和地表特征参数的分布。

Dealing with regional land surface parameters and radiation balance components is a very important and difficult task. Studying on land surface parameters and components of surface radiation balance over inhomogeneous landscape, the utilization of satellite remote sensing is indispensable. In this study, a parameterization method based on Landsat7 ETM＋ data and 22 weather stations data is described for deriving the regional distributions of land surface parameters （NDVI, surface reflectance, surface temperature） and components of surface radiation balance （surface absorbed shortwave radiation, surface upward longwave radiation, downward atmospheric radiation, net radiation） over the southern Ningxia region. Distribution map and histograms of the parameters and components are given. Furthermore, the southern Ningxia region is classified into five surface types, regional distributions of land surface parameters and components of surface radiation balance are discussed according to each type. The results indicate： （1） All the regional distributions are characteristic in their terrain nature and the regional distributions are obvious and regular. The maps of mountains and rivers are very clear with dense vegetations growing on the mountains and by the rivers. It is seen that the derived regional distributions of land surface parameters and components of surface radiation balance for the whole mesoscale area are well in accord with the land surface status. （2） The maximum NDVI is on the Liupan mountains （with a forest）followed by the Yueliang mountain and rivers and other irrigated areas （with grass or crops）, and the low NDVI value area over water bodies and nudation. （3）The regional distributions of surface reflectance and surface temperature are basically in-phase opposition with the corresponding regional distributions of NDVI. （4）The surface absorbed shortwave radiation is high over the Liupan mountain, the Yueliang mountain and by the rivers, and the nudation is low. On clear day, the surface absorbed shortwave radiation is mainly determined by surface reflectance. The regional distribution of net radiation is similar to the surface absorbed shortwave distribution.