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设置合理的冠层辐射传输参数有利于地表能量过程的真实表达,将对改善陆面过程模型模拟精度起到重要作用。基于2008年和2012年锦州农田生态系统的通量、气象及生物因子连续观测,分析了玉米农田叶面积指数、植被覆盖度、平均叶倾角、叶片反射率和透射率动态变化规律及各因子间的关系,对CoLM模型辐射传输参数进行优化,并对模型优化效果进行定量评价。结果表明:叶面积指数与植被覆盖度和平均叶倾角分别呈幂函数和二次函数关系;平均叶倾角的参数优化对模型模拟几乎没有影响;叶片反射率和透射率优化后,冠层反照率模拟精度明显提高;净辐射、感热模拟值对实测值解释能力分别提高0.6%和4.0%,Nash-Sutcliffes系数增大0.008和0.028,相对均方差(RRMSE)减小0.068和0.050;潜热模拟精度改善程度小于感热,地表热通量未表现出改善。
Setting a reasonable canopy radiation transmission parameters is conducive to the true expression of the surface energy process and will play an important role in improving the simulation accuracy of the land surface process model. Based on the continuous observation of flux, meteorology and biological factors of farmland ecosystem in Jinzhou in 2008 and 2012, the dynamic change law of leaf area index, vegetation coverage, average leaf inclination, leaf reflectance and transmissivity of maize farmland was analyzed. , The parameters of CoLM model radiation transmission are optimized, and the effect of model optimization is quantitatively evaluated. The results showed that leaf area index, vegetation coverage and average leaf inclination were power function and quadratic function respectively. The parameter optimization of average leaf inclination had almost no effect on model simulation. After the optimization of leaf reflectivity and transmissivity, the canopy albedo The simulated accuracy of net radiation and sensible heat increased by 0.6% and 4.0% respectively, the Nash-Sutcliffes coefficient increased by 0.008 and 0.028, and the relative mean square error (RRMSE) decreased by 0.068 and 0.050 respectively. The simulation accuracy of latent heat The improvement is less than sensible heat, and the surface heat flux does not show any improvement.