静止轨道热红外波段自主在轨参考基准:交叉传递与精度改进

The performance assessment for observations in thermal infrared band of Fengyun satellites is always accomplished by intercalibration with a certain referenced standard, while it is critical in need of multisource observations uniformed by a referenced standard for decadal climate change monitoring. Up to now, however, all the on-orbit referenced standards belong to EU or U.S. In this proposed project, the first infrared hyperspectral sensor (GIIRS) on the geostationary platform in the worldwide, which is onboard on FY-4A satellite, is selected to be the referenced standard for a universal framework model for radiometric standard transfer among different sensors. These sensors can be equipped on the different or the same platform(s), can be with the different or the comparable spatial resolution(s), and can be hyperspectral/wide-band/narrow-band ones. The radiometric standard of GIIRS can be traced to the International System of Units by the specialized bi-directional transfer processes, i.e. transferred (or called monitored in the above framework model) and referenced ones. In our studies, a universal spatial and spectral collocation models are originally proposed based on the two key technologies, i.e. spatial overlapping identification and its feature extraction on the order of pixel scale, and spectral radiance estimation by using convolution with the matched information between different instrument line shapes of hyperspectral sensors. To achieve the high consistency as well as the low uncertainty performance of observations from GIIRS, two vital scientific issues, i.e. dynamic sampling in the interferometric domain and the corresponding reconstruction, and correction to the back-ground radiation with complex variation in temporal- and spatial- domains, are scheduled to be solved. Moreover, by examining the consistency and facticity of some typical long-term serial products generated by the multisource observations transferred by GIIRS, its reliability acting as a referenced standard can be evaluated. The main researches are highly original, the outcomes of which can promote GIIRS to become a member of the international referenced sensor group eventually.

风云卫星热红外波段观测性能评价一直依赖与参考基准的交叉定标来实现，十年际气候变化监测亟需统一参考基准的多源卫星观测，但迄今在轨参考基准完全被欧美垄断。选择风云四号A星上全球首台静止轨道红外高光谱遥感器（GIIRS）为参考基准，建立普遍适用于不同/相同卫星平台、不同/相当空间分辨率、高光谱/宽波段/窄波段遥感器间辐射基准传递框架模型，通过“被传递”和“被参考”的双向传递可实现在轨溯源至国际基本单位。其中，提出以像元级空间覆盖辨识与特征提取、基于仪器线形函数匹配后卷积的谱辐射估计等为核心的通用空间与光谱匹配模型；解决实现GIIRS观测高一致性和低不确定度的干涉域动态采样与重构、时空维度复杂变化背景辐射校正等关键科学问题。同时，通过检验由基准传递后多源观测导出的长时间序列典型产品的一致性和真实性，来评估GIIRS作为参考基准的可靠性。主要研究属于原创性工作,将推动GIIRS进入国际参考仪器序列。

围绕建立国产自主空间红外辐射参考基准的迫切需求，以风云四号A星上装载的全球首台静止轨道红外高光谱探测仪（GIIRS）为参考仪器，在全面改进GIIRS观测数据光谱与辐射精度并充分验证其一致性与有效性的基础上，发展了普适的不同卫星平台、不同空间和光谱分辨率组合下的空间遥感器间辐射基准传递框架模型。主要研究内容和重要成果包括：1）攻克了异构大面阵条件下GIIRS观测资料的高精度光谱与辐射定标难题并业务化应用，光谱定标精度优于10ppm，辐射定标精度优于1K，完全满足数值天气预报应用需求，为国际后续类似遥感器数据处理提供参考，实现了中国科学家首获国际气象观测领域最高奖项的突破；2）提出了面向GIIRS的云检测与云高指定、大气温度和湿度廓线产品等反演算法，证实了在有轻微污染条件下，GIIRS观测资料仍有很强的探测能力；3）发展了不同卫星平台、不同光谱与空间分辨率组合下不同红外遥感器与GIIRS间的辐射基准传递模型，并在风云四号A星中实现初步应用。其中，多通道成像辐射计（AGRI）与GIIRS的相对辐射基准偏差小于0.2K；4）突破了传统红外辐射定标依赖黑体辐射参考源的方法，提出恒温恒压下采用单元探测器的热红外遥感器在轨无源定标方法新方法业务化应用，实现了国际第一代静止气象卫星红外辐射定标性能的最好水平。在本项目支持下，GIIRS观测数据质量显著提升，得到了国际权威机构高度评价，被列为风云气象卫星五十年成就中实现国际领跑的标志性成果。在本项目研究期内，项目组成员共发表SCI收录论文8篇、核心期刊论文1篇；获国家发明专利2项；培养博士生1名、硕士生4名，晋升正高职称2人、副高职称1人；获国际气象观测领域最高奖1项、省部级科技进步二等奖1项、省部级人才奖2项。