太赫兹火星大气临边探测仿真研究

对火星大气进行连续高分辨率观测是研究火星大气物理和化学过程的重要手段.太赫兹临边探测技术通过测量火星大气中的风和光化学循环中的重要气体（CO，O₃，H₂O，H₂O₂等）提高对火星的认知.针对火星大气遥感的探测需求，分析了300～1000GHz频段的频谱特征.针对探测卫星对于载荷质量、功耗等参数的要求，提出一个560GHz频段的火星大气太赫兹临边探测仪设计方案，并利用辐射传输模型ARTS中的行星工具箱进行仿真.仿真结果显示:火星大气温度的反演精度优于4K，其中45km高度以下优于2K；H₂O丰度的反演精度在90km以下优于50%，30km以下优于2%；H₂O₂的反演精度在40km以下优于50%；O₃的反演精度在50km以下优于60%；大气风速度的反演精度在65km以上优于5m·s-1，最高可以达到2m·s-1.研究结果表明，利用太赫兹波段的吸收谱线可以很好地探测火星大气中各成分的丰度、变化趋势以及中高层大气的风，可为后续火星表面及大气探测提供参考. 

Martian Atmosphere Study Using THz Limb Sounder

Mars is one of the main targets of deep space exploration. Continuous and high spatial resolution global monitoring of Martian atmosphere is an important way to understand the aeronomy and meteorology of Mars. The atmospheric wind and chemical species in the photochemical cycle such as CO, O₃, H₂O, H₂O₂ can be measured in large scale by Terahertz limb sounding technique to improve our understanding of Martian atmospheric chemistry and dynamics. The spectrum in the frequency region of 300~1000GHz is analyzed according to the request of Mars exploration. Considering the requirements of the satellite on the parameters of load weight and power, a Martian atmosphere THz limb sounder working in the frequency of 547~579GHz is proposed. The planetary toolbox of ARTS is used to simulate the performance of the instrument. Results show that by using CO lines to retrieve the temperature profile, the total precision can be < 4K. The precision is < 2K at an altitude below 45km. The retrieval precision of H₂O is < 50% at an altitude below 50km, and the best precision is 2%. The retrieval precision of H₂O₂ is < 50% below 40km. The retrieval precision of O₃ is < 60% below 50km. The retrieval precision of the atmospheric line of sight wind is < 5m·s-1 above 65km, and the best precision is 2m·s-1. In conclusion, the middle and upper atmospheric wind and the abundance of the chemical species can be well measured by using THz limb sounding technique.