【目的】检验SCOPE(Soil Canopy Observation of Photosynthesis and Energy fluxes)模型用于模拟樟子松人工林的日光诱导叶绿素荧光(sun-induced chlorophyll fluorescence,SIF)和植被总初级生产力(gross primary productivity,GPP)动...【目的】检验SCOPE(Soil Canopy Observation of Photosynthesis and Energy fluxes)模型用于模拟樟子松人工林的日光诱导叶绿素荧光(sun-induced chlorophyll fluorescence,SIF)和植被总初级生产力(gross primary productivity,GPP)动态变化的可能性。【方法】对科尔沁沙地南缘樟子松人工林,基于样地SIF、GPP及气象协同观测数据,利用SCOPE模型模拟SIF与GPP的日变化与季节变化,评估了SCOPE模型在典型晴天、典型多云日、整个观测期的模拟效果。【结果】结果显示,利用气象观测数据及冠层参数(入射短波辐射、气温、大气实际水汽压、CO_(2)浓度及叶面积指数),可驱动SCOPE模型模拟樟子松人工林的SIF与GPP。典型晴天日与多云日的SIF模拟值和实测值的R^(2)分别为0.42与0.52,RMSE分别为0.19与0.18 W·m^(-2)·μm^(-1)·sr^(-1);GPP模拟值和观测值的R^(2)分别为0.78与0.89,RMSE分别为1.87与2.57μmol·m^(-2)·s^(-1)。在季节尺度上,SIF和GPP模拟值和观测值的R^(2)分别为0.50、0.72,RMSE分别为0.19 W·m^(-2)·μm^(-1)·sr^(-1)和2.64μmol·m^(-2)·s^(-1)。在整个观测期,多云日的SIF(R^(2)=0.31,RMSE=0.22 W·m^(-2)·μm^(-1)·sr^(-1))与GPP(R^(2)=0.80,RMSE=2.42μmol·m^(-2)·s^(-1))的模拟效果优于晴天日(SIF:R^(2)=0.30,RMSE=0.26 W·m^(-2)·μm^(-1)·sr^(-1),GPP:R^(2)=0.64,RMSE=3.64μmol·m^(-2)·s^(-1))。SIF模拟值总体高于观测值,当SIF强度较低时易对SIF高估,反之则易低估。GPP的模拟精度较高,模型对较低与较高GPP有所低估,对中间值有所高估。【结论】SCOPE模型可用于日尺度与季节尺度的SIF与GPP模拟,且多云日的模拟精度更高。SCOPE模型对樟子松人工林的GPP模拟结果优于SIF,推测SIF模拟精度较低的原因可能是模型对SIF的模拟是基于阔叶植物的辐射传输过程。未来应发展针对针叶植物的SIF辐射传输模型,为针叶林的辐射传输与荧光遥感监测提供模型基础。展开更多
If we take Chinese modern literary history( female) as the"center",in which the female creation is very limited,a large amount of female compositions in late Qing Dynasty and R epublican period were "ma...If we take Chinese modern literary history( female) as the"center",in which the female creation is very limited,a large amount of female compositions in late Qing Dynasty and R epublican period were "marginalized",even in the "hidden "state. These "marginalized"female writings,not only are in a large number,but also constitute the foundation of Chinese modern female literature creation,the significance and value cannot be ignored. To seek the strategy and approach for the research on the "marginalized"female creation in late Qing Dynasty and R epublican period,helps to deeply discuss the possibility to expand the object scope of female literature research,to find a newgrowing point of female literature research,and form conversation between female literary history writing and current theory and practice of the"R ewriting Literary History".展开更多
叶绿素作为植物光合作用的主体,在监测植被生长状态,评估固碳能力方面发挥着巨大的作用。遥感技术作为一种高效低成本的对地观测技术,能够通过叶片反射光谱特征实现叶绿素含量(chlorophyll content,Cab,含量为面密度)的估算。然而,叶片...叶绿素作为植物光合作用的主体,在监测植被生长状态,评估固碳能力方面发挥着巨大的作用。遥感技术作为一种高效低成本的对地观测技术,能够通过叶片反射光谱特征实现叶绿素含量(chlorophyll content,Cab,含量为面密度)的估算。然而,叶片光谱会受到叶片含水量、叶细胞结构等影响,从而降低遥感估算Cab的精度。而日光诱导叶绿素荧光(solar-induced chlorophyll fluorescence,SIF)遥感是直接探测叶绿素激发荧光信息,其变化特征与Cab直接相关,在Cab估算中有巨大的潜力。为此,以荧光辐射传输模型(soil canopy observation,photo-chemistry and energy fluxes,SCOPE)为工具,通过敏感性分析确定Cab荧光敏感波段,并建立基于荧光光谱的Cab估算模型,最后利用实测数据验证模型的鲁棒性。研究结果表明,700、730 nm分别为叶绿素高、低敏感波段(SIF_(700)、SIF_(730)),760 nm为叶绿素高相关性波段(SIF_(760)),以此3波段建立基于荧光比值的Cab估算模型,其中,以SIF_(760)与SIF_(700)的荧光比值建模精度最优,决定系数R2为0.9981,均方根误差(root mean square error,RMSE)为0.0435μg/cm^(2)。SIF_(700)与SIF_(730)荧光比值和Cab的建模精度最低,但R2和RMSE也分别达到了0.9048和0.0886μg/cm^(2)。利用实测数据独立样本对上述3种估算方法进行验证,SIF_(760)/SIF_(730)估算结果表现最佳,RMSE为0.2108μg/cm^(2),SIF_(700)/SIF_(730)次之,RMSE为0.3454μg/cm^(2),但呈现出整体高估现象;SIF_(760)/SIF_(700)估算结果与实测数据偏差较大,RMSE为0.7435μg/cm^(2)。综上,SIF_(760)/SIF_(730)构建的比值植被指数在估算Cab过程中不仅能够保证很好的建模精度,同时又表现出极佳的鲁棒性。研究结果为利用叶绿素荧光遥感手段进行叶片生化参数估算提供技术参考。展开更多
文摘If we take Chinese modern literary history( female) as the"center",in which the female creation is very limited,a large amount of female compositions in late Qing Dynasty and R epublican period were "marginalized",even in the "hidden "state. These "marginalized"female writings,not only are in a large number,but also constitute the foundation of Chinese modern female literature creation,the significance and value cannot be ignored. To seek the strategy and approach for the research on the "marginalized"female creation in late Qing Dynasty and R epublican period,helps to deeply discuss the possibility to expand the object scope of female literature research,to find a newgrowing point of female literature research,and form conversation between female literary history writing and current theory and practice of the"R ewriting Literary History".
文摘叶绿素作为植物光合作用的主体,在监测植被生长状态,评估固碳能力方面发挥着巨大的作用。遥感技术作为一种高效低成本的对地观测技术,能够通过叶片反射光谱特征实现叶绿素含量(chlorophyll content,Cab,含量为面密度)的估算。然而,叶片光谱会受到叶片含水量、叶细胞结构等影响,从而降低遥感估算Cab的精度。而日光诱导叶绿素荧光(solar-induced chlorophyll fluorescence,SIF)遥感是直接探测叶绿素激发荧光信息,其变化特征与Cab直接相关,在Cab估算中有巨大的潜力。为此,以荧光辐射传输模型(soil canopy observation,photo-chemistry and energy fluxes,SCOPE)为工具,通过敏感性分析确定Cab荧光敏感波段,并建立基于荧光光谱的Cab估算模型,最后利用实测数据验证模型的鲁棒性。研究结果表明,700、730 nm分别为叶绿素高、低敏感波段(SIF_(700)、SIF_(730)),760 nm为叶绿素高相关性波段(SIF_(760)),以此3波段建立基于荧光比值的Cab估算模型,其中,以SIF_(760)与SIF_(700)的荧光比值建模精度最优,决定系数R2为0.9981,均方根误差(root mean square error,RMSE)为0.0435μg/cm^(2)。SIF_(700)与SIF_(730)荧光比值和Cab的建模精度最低,但R2和RMSE也分别达到了0.9048和0.0886μg/cm^(2)。利用实测数据独立样本对上述3种估算方法进行验证,SIF_(760)/SIF_(730)估算结果表现最佳,RMSE为0.2108μg/cm^(2),SIF_(700)/SIF_(730)次之,RMSE为0.3454μg/cm^(2),但呈现出整体高估现象;SIF_(760)/SIF_(700)估算结果与实测数据偏差较大,RMSE为0.7435μg/cm^(2)。综上,SIF_(760)/SIF_(730)构建的比值植被指数在估算Cab过程中不仅能够保证很好的建模精度,同时又表现出极佳的鲁棒性。研究结果为利用叶绿素荧光遥感手段进行叶片生化参数估算提供技术参考。
