陆面模拟中植被辐射传输参数化方案研究  

A study on the radiative transfer parameterization scheme within canopy in land surface process model

作　　者：周文艳[1] 郭品文[1] 罗勇[2] Kuo-Nan Liou Gu Yu Xue Yongkang 

机构地区：[1]南京信息工程大学,南京210044 [2]中国气象局国家气候中心气候研究开放实验室,北京100081 [3]University of California, Los Angeles,US

出　　处：《气象学报》2008年第3期359-370,共12页Acta Meteorologica Sinica

基　　金：国家自然科学基金项目(40375026);江苏省高校研究生创新计划项目;国家自然科学基金重点项目(40233034);国家气候中心陆面模式项目

摘　　要：在冠层二流辐射传输模式基础上新发展了一个描述太阳短波辐射在植被中传输的冠层四流辐射传输模式。冠层四流辐射传输模式是在大气辐射传输理论的基础上得到一组描述短波辐射在植被中传输过程的冠层辐射传输基本方程,引进大气中求解辐射传输方程的四流近似解法,并求得冠层四流辐射传输方程的解析解。方程中各项参量能够反映叶子或冠层特殊的几何和光学特征。冠层向上、向下辐射通量取决于冠层散射相函数、叶子在入射光方向投影面积、单个叶子反射率和透射率、叶面积指数以及直射光入射太阳高度角等。四流模式计算叶子水平倾角时对太阳短波辐射的反照率,与二流模式结果比较可以验证模式的理论推导和建模都是正确的:计算结果的比较,表明四流模式在水平叶角分布时计算的冠层反照率与二流模式结果一致,同时直射光从任何太阳高度角入射的冠层反照率结果也一致,从而证明发展的冠层四流辐射传输模式是成功的。模拟试验中将两种模型同时耦合到同一个陆面过程模式中进行比较试验,结果表明,冠层四流辐射传输模式能够得到更精确的植被反照率,从而使得陆面模式计算的地表吸收的净太阳辐射通量更接近于观测值。A four-stream solar radiative transfer model within canopy in land surface process model was developed.The four-stream approximation method of atmospheric radiation equation is used to gain the analytic solutions of the basic equation of radiative transfer within canopy.The four-stream solar radiative transfer model within canopy is based on the two-stream short wave radiative transfer model.The radiative transfer theory within canopy is based on the radiative transfer theory in atmosphere.Each parameter of the basic equation of canopy has the special geometry and optical character of leaf or canopy.The upward or downward radiative fluxes are related to the diffuse phase function,G-function,leaf reflectivity and transmission,leaf area index,and solar altitude angle of incident beam.The computed results of the albedo of canopy on the condition of horizontal leaf from new developed four-stream radiative model within canopy and the original two-stream model are compared,and the four-stream model is proved to be successful by the same modelling results of the canopy albedo of the any solar incident angle.The paper carries out one experiment to evaluate the simulations of the land surface model simultaneously coupled with the both radiative transfer models.The test indicates that the simulation of land surface process model coupled with four-stream model is better than two-stream radiative transfer model,since the computed solar radiation absorption of land surface is closer to the observation.

关 键 词：冠层辐射传输方程 四流近似 四流辐射模式 

分 类 号：P422[天文地球—大气科学及气象学] P463.22