基于风云三号卫星60GHz和118GHz探测数据的大气氧气吸收差异分析及其融合研究

在微波波段，60和118GHz是氧气的两个重要吸收峰，可用于大气温度廓线的探测。60GHz已业务应用多年，在数值天气预报和环境监测等方面发挥了重要作用。近年来，中国风云三号卫星新一代微波湿度计，首次把118GHz作为主要通道并业务运行。与60GHz相比，118GHz氧气吸收特性和更高的频率特性，使其在获取大气温度信息方面具有新的特征。本项目拟基于风云三号卫星微波温度计II型和微波湿温探测仪观测资料对60和118GHz氧气吸收特性差异及其融合反演大气温度廓线开展以下研究：基于辐射传输理论对两个载荷温度通道权重函数的分布特征进行模拟和建模，提取通道亮温的变化特征并进行差异分析；针对模拟亮温与实际观测亮温之间的偏差，建立非线性统计校正算法，减少系统定标残差和模型的非理想化误差；在此基础上，建立物理反演算法，挖掘60和118GHz温度探测优势的互补性，提出融合反演大气温度廓线的最优通道组合。本项目的预期研究成果可实现60和118GHz温度探测优势互补，为大气科学领域的各种应用和科学研究提供高精度的大气温度廓线，同时可为大气温度探测数据的应用和后续探测仪器的硬件开发提供理论指导和重要参考。

In the microwave band, the 60 GHz and 118 GHz are two significant oxygen absorption lines, which can be used to detect atmospheric temperature. The 60 GHz absorption line has been used for the operational application for many years, which plays an important role in numerical weather prediction and environmental monitoring. A new generation of the Microwave Humidity Sounder onboard the China Fengyun-3 satellite takes the 118 GHz absorption line as the important channel for the first time and put into business operation. Compared with the 60 GHz absorption line, the absorption and frequency characteristics of 118 GHz make its own new features in detecting the atmospheric temperature. Based on the observations of Microwave Temperature Sounder-II (MWTS-II) and Microwave Humidity and Temperature Sounder (MWHTS) onboard the Fengyun-3 satellite, we study the absorption characteristic differences between the 60 GHz and 118 GHz absorption lines and retrieve the atmospheric temperature profiles using the 60 GHz and 118 GHz combined observations. This study mainly contains three parts. Firstly, the distribution features of the MWTS-II and MWHTS sounders’ weighting function are simulated and modeled by radiative transfer theory in different atmospheric states. Then, for the bias between the simulated and observed brightness temperature, a nonlinear correction method is proposed to reduce the calibration residual and the bias of the radiative transfer model. Based on the MWTS-II and MWHTS sounders’ channel characteristics and the nonlinear bias correction method, a physical retrieval algorithm is proposed to study the complementarity of sounding temperature using the 60 GHz and 118 GHz absorption lines. Finally, an optimized channel combination of 60 GHz and 118 GHz is created for the retrieval of the atmospheric temperature profiles. The expected result is to realize the complementarity of sounding temperature based on the 60 GHz and 118 GHz absorption lines which provides high precision atmospheric temperature profiles for application and research in the field of atmospheric science, and provides theoretical guidance and an important reference for the hardware development of detection instruments and the application of the temperature sounding observations.