基于双波段闪烁仪法获取大尺度地表水热通量的研究

Accurate and reliable water vapor and heat flux (1-5 km) at large scale can solve the scale mismatch between ground observations and remote sensing estimations, and promote the precision improvement of related remote sensing products and development of remote sensing models. It is the hot spot and difficult issue in validation of remote sensing products. Dual-band (near infrared & microwave) method, namely the optical/microwave scintillometer (OMS), provides an important way to acquire water vapor and heat flux at large scale. This method is based on the optical propagation theory in the atmosphere and the turbulence Monin-Obukhov similarity theory, and the fluxes can be calculated combing the micro-meteorology observations and other parameters. However, there were numerous uncertainties due to the complexity of turbulent motion and the method litimations. This project takes the alpine meadow in Qinghai and the plantation forest in the southern of North China as the research objects. The observation technique and method of OMS were investigated. In addition, we explore the data processing and quality algorithm of OMS system, and the continuous and reliable water vapor and heat flux at large scale can be acquired. Moreover, the uncertainties and influence mechanism of water vapor and heat fluxes by OMS system were obtained through comparing to the eddy covariance measurements. Finally, the water vapor and heat fluxes at large scale were applied on the validation of the remotely sensed evapotranspiration products, which can promote the improvement of the remote sensing models and relate products.

获取准确、可靠的大尺度地表水热通量（1-5 km）能够有效解决地面观测值与遥感估算值空间尺度不匹配的问题，促进相关遥感产品精度的提高以及遥感估算模型的发展，是目前遥感产品真实性检验研究的热点与难点问题。双波段（近红外+微波波段）闪烁仪法基于大气光传播理论与湍流相似理论，并结合微气象参数等测算出地表水热通量，为大尺度地表水热通量的获取提供了可靠途径。但是，由于大气湍流运动的复杂性及方法本身的限制，测量结果存在较多的不确定性。本项目选择青海高寒草地和华北南部人工森林为研究对象，研究双波段闪烁仪的观测技术与方法，研制观测数据处理与质量控制算法，并获取连续、可靠的大尺度地表水热通量；通过与涡动相关仪观测值比较，评价其不确定性并分析影响机制；最后，将获取的大尺度地表水热通量应用于地表蒸散发遥感产品的验证中，促进地表蒸散发遥感估算模型与相应产品的改进。

双波段闪烁仪是直接获取大尺度地表水热通量（1-5km）最为有效的地面观测手段，但在实际观测中仍存在一定的问题。本项目依托在黑河流域上游高寒草甸下垫面和中游绿洲荒漠区域玉米下垫面开展的双波段闪烁仪及其配套参数的观测试验，制定了双波段闪烁仪的观测规范，研发了数据处理与质量控制算法，并在均匀下垫面对算法进行了验证，获得了较为连续、可靠的大尺度地表水热（感热和潜热）通量。分析了大尺度感热和潜热通量的日、季节变化特征，同时与涡动相关仪测量的数据进行了对比，结果表明：在高寒草甸均匀下垫面不同尺度感热和潜热通量均较为一致；在绿洲荒漠区域玉米下垫面，不同尺度的水热通量差异较大，尤其在作物生长季的潜热通量，导致这种现象主要是由于下垫面的非均匀性导致的，同时也发现闪烁仪可显著提高地表能量平衡闭合率，表明闪烁仪在非均匀地表应用具有更大的优势。量化了黑河流域多尺度蒸散发的时空变化特征，并探讨了影响机制。已发表学术论文5篇，其中SCI论文4篇。撰写英文书稿章节1个，获得软件著作权1项，国家标准1项。参加国内会议6人次，国际会议1人次。获取的观测数据可用于遥感产品的真实性检验，促进地表蒸散发等相关遥感估算模型与相应产品算法的改进。