温室气体廓线高精度激光外差光谱测量技术研究

High-precision atmospheric profile detection instrument is of great significance for verifying satellite observation results and accurately obtaining global greenhouse gas concentration distribution, especially for mastering the initiative in global climate negotiations. The compact laser heterodyne radiation detection system is more suitable to meet the needs of mobile high-precision atmospheric profile detection instrument for China's complex geographical environment than the ground-based Fourier transform spectrometer. However, there are some problems of measurement of atmospheric profile with high precision and high temporal resolution in high resolution laser heterodyne detection system. Then, this project intends to study semiconductor optical amplification technology based laser heterodyne spectroscopy to solve the limit of the heterodyne signal to noise ratio (SNR) improvement due to the optical antenna theory, and to improve the heterodyne signal SNR for enhancing the precision of atmospheric profile retrieval and the response time of the system. In terms of the problem that the theoretical calculation error of instrument lineshape function exists in the traditional laser heterodyne radiation detection system, this project uses a heterodyne laser with narrow linewidth (< 1kHz) as the signal light to study the measurement method of instrument linear function of the system to ensure the accuracy of the retrieved atmospheric profile. Based on the above research, the application of high-resolution laser heterodyne radiation detection system in the field of atmospheric detection would be further promoted.

高精度温室气体廓线探测设备对于卫星观测结果校验，准确获取全球温室气体浓度分布并掌握在全球气候谈判中的主动权具有重要意义。相比地基傅里叶变换光谱仪，小型化激光外差辐射探测系统更能满足我国复杂地理环境对可移动高精度温室气体廓线探测设备的需求。针对当前高分辨率激光外差辐射探测系统存在高时间分辨率、高精度测量大气廓线时存在的问题，在激光产生原理的启发下，本项目拟开展基于半导体光放大技术的激光外差光谱技术研究，解决当前激光外差探测光学天线理论限制的外差信号信噪比提高难的问题，以提高外差信号信噪比，从而提高廓线的测量精度，同时兼顾系统响应时间；针对传统激光外差辐射探测系统仪器线型函数理论计算误差大的问题，本项目以窄线宽(<1KHz)的外差激光器作为信号光，开展激光外差辐射探测系统仪器线型函数测量方法研究，减小廓线测量误差。基于以上研究，将进一步推广高分辨激光外差辐射探测系统在大气探测领域的应用。

本项目针对我国复杂地理环境对可移动高精度大气廓线观测设备的需求，开展了温室气体廓线高精度激光外差光谱测量技术研究。首先，针对当前激光外差探测中光学天线理论限制的外差信噪比提高难题，开展了融合半导体光放大技术的激光外差光谱技术研究，研究了外差信噪比提高了7.7倍，系统探测灵敏度提高了9.3倍，温室气体测量精度提高了7.6倍。其次，系统研究了仪器线型误差对温室气体反演精度的影响，并开展了高精度系统仪器线型函数测量方法研究，为外差光谱反演提供了精准模型输入。最后，项目集成了一套小型化的激光外差温室气体廓线测量系统，并建立了一套集系统控制、数据采集与外差光谱分析的垂直廓线在线反演软件，并对合肥地区大气CO2廓线进行了连续实时反演，所测得的数据揭示了大气CO2输送过程。已发表相关研究论文3篇。

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