高分热像数据和光谱数据的植被气孔导度反演机理研究

Plant leaf stomata is an important channel controlling the energy and water exchanges between canopy and atmosphere. There is extensive envidence that leaf/canpony stomatal conductance is a key factor controlling both photosynthesis intensity and transpiration rate which will have large impacts on both productivity and plant qulity.Mechanism of stomatal closure is affected by many factors both plant itself and the environment. Conventional method with porometer for surveying stomatal conductance can not meet the requirements of monitoring large region.Based on the energy balance model, around the core issue between the stomatal conductance and the reflection/radiation, it has an important scientific significance to establish a quantitative relationship model of leaf/canopy stomatal conductance based on hyperspectral and infrared thermal data. Through the processing of innovative experiments, statistical analysis, the mechanism of derivation, model and validation, the main study contents are designed as follows. (1) Research the basic theories and methods of stomatal conductance inversion model using thermal imaging data. A stomatal conductance inversion model will be established using infrared thermal image data though the experiment, data simulation and validation using the measurement instruments, including infrared camera, porometer, etc. (2) The stomatal structure and spectral characteristic parameters of leaf can be obtained simultaneously using the non-invasive method. Then, the relationship model can be built between the leaf stomatal conductance and stomatal characteristics parameters and vegetation indices to improve retrieval accuracy of stomatalconductance through remote sensing methods.

气孔是植物叶片与环境进行物质交换的重要通道，叶片/冠层气孔导度是决定光合作用强度和水分蒸腾强度进而影响作物产量和品质的重要因子，是描述植物生理生态的重要参数之一。常规的气孔计获取气孔导度的监测手段已经不能满足要求，作物的活动面（叶片/冠层）是蕴含遥感信息的辐射面和反射面，也是作物生理特征参数的表征面，基于能量平衡模型，围绕气孔导度变化会引起叶片反射和辐射变化响应这一核心问题，建立基于高光谱与热像数据的叶片/冠层气孔导度反演模型。通过创新实验、统计分析、机理推导、模型建立和实例验证等过程，主要研究以下内容：（1）高分热像数据反演气孔导度模型的基本理论与方法，包括利用红外热像仪、气孔计，通过控制试验和数据模拟及验证，建立红外热像数据反演气孔导度模型，（2）利用非损伤方法同步获取叶片气孔结构和光谱特征参数，建立气孔导度与叶片气孔特征定量参数和植被指数关系模型，提高导度反演精度。

气孔是植物叶片与环境进行物质交换的重要通道，是描述植物生理生态的重要参数之一。常规气孔导度的监测手段已经不能满足要求，通过野外高光测量、光合作用测量、红外热像测量、统计分析、机理推导、模型建立和实例验证等过程，对高光谱与热像数据的叶片/冠层气孔导度反演机理有了深入的认识。（1）构建了非损伤方法获取叶片气孔主要特征参数模型，（2）构建了多种作物气孔特征参数估算模型，（3）归一化植被指数计算差异的定量评价与叶面积指数估算模型，认为NDVI的定义差异不可忽视（4）对热红外通道和短波红外通道温度反演模型进行改进，构建了新的雪指数模型ENDSI，利用SVISSR/FY-2C提出了陆地地表温度与比辐射率反演模型。（5））多角度反射测试自动平台构建，实现了地物光谱特性的多角度全方位观测。