基于短波红外与热红外卫星观测的边界层CO2浓度联合反演方法研究

Satellite remote sensing can supply measurements of regional CO2 distribution. However, boundary CO2 concentration cannot be inversed directly from satellite observations in short-wavelength infrared (SWIR) band or infrared (IR) band due to the spectral character of observing channel. Combining the advantage of satellite observations in SWIR and IR bands, we aim to develop a joint inverse method to retrieve boundary CO2. First, our approach makes channel selection according to CO2 weighting function. Second, we will simulate satellite observations under heavily air-polluted condition. Analyzing the impact mechanism of aerosol and temperature to observations, we try to design a new method to parameterize the impacts from aerosol and temperature and the parametric factors will be used to modify the radiative transfer function. Then, we will construct an optimal joint inverse method by comparing the performance of different joint manners. The joint inverse method will be tested using satellite observations and the validations to ground-based measurements are made to improve the joint invers method. Finally, long-term boundary CO2 retrieval will be released and used for CO2 emission and source and sink study.

高光谱卫星遥感技术可以提供CO2浓度空间分布监测数据，然而受通道光谱特征影响，无论短波红外还是热红外卫星观测，都无法直接反演边界层CO2浓度。本项目依据短波红外与热红外CO2遥感各自的优势，研究一种卫星联合反演算法，以获取边界层CO2浓度。首先，根据CO2通道的权重分布特征，选择联合反演通道；其次，针对重污染大气背景，分析气溶胶散射与温度对短波红外与热红外CO2卫星遥感的影响机制，建立全新的参数化模型估算气溶胶与温度带来的‘噪声’，并利用参数化因子修正大气有效透过率模型；最后，研究分析短波红外与热红外联合反演的模式，建立卫星边界层CO2浓度反演模型，基于修正的大气有效透过率模型，开展卫星反演与验证，完善联合反演算法。生产我国区域内边界层CO2浓度卫星反演产品，支撑CO2排放核查与源、汇分析。

在全球变暖与气候变化大背景下，国际社会围绕温室气体的减排与控制达成了广泛的共识，并签署了一系列的排放协议。针对碳排放的评估，需要发展时空连续的精准卫星监测技术。人为排放产生的碳的源、汇主要发生在近地层大气，我国作为碳排放大国，迫切需要针对近地层大气CO2的卫星遥感监测反演技术。项目依托已有的温室气体在轨遥感平台，综合短波红外通道和热红外通道对CO2的垂直敏感性分布特征，选择短波红外和热红外联合反演通道；提出了改进的最优化非线性迭代模型；采用基于等效理论的参数化估计方法，估算污染大气环境下短波红外通道的气溶胶散射效应，改进了原有经验模型；对于温度的影响，提出了温度与CO2浓度同步反演策略，构建了短波红外与热红外联合的低层大气CO2卫星反演模型，为在我国“双碳”战略提供监测技术支撑。