Using Onion-Peeling Method to Inverse Ozone Density Based on the Stellar Occultation Technology in the Near Space Region
ZHANG Si-min1，2，3, WU Xiao-cheng1，2，3*, SUN Ming-chen1，2，3, HU Xiong1，3, GONG Xiao-yan1，3
1. National Space Science Center, Chinese Academy of Sciences，Beijing 100190, China
2. University of Chinese Academy of Sciences，Beijing 100049, China
3. Key Laboratory of Science and Technology on Environmental Space Situation Awareness, Chinese Academy of Sciences，Beijing 100190, China
摘要： 星光掩星技术探测恒星光经大气层消光、折射等作用后的恒星光光谱，利用大气中不同成分对不同波长的光吸收的差异反演得到大气密度信息。低轨卫星与恒星分别位于地球两侧，低轨卫星接收到不同切线高度上光谱，即构成星光掩星观测。光谱探测高度可从平流层至低热层，其中不同波段可用于不同大气痕量成分密度反演。星光掩星技术具有探测参数多、全球覆盖、垂直分辨率高、无需定标等优点。GOMOS(global ozone monitoring by occultation of stars)是搭载在欧洲航天局ENVISAT卫星上的平流层臭氧检测仪器。GOMOS利用星光掩星技术进行探测，设计精密，分辨率高，在轨稳定运行十年（2002年—2012年），探测波长跨越紫外到可见光波段，采用光谱反演和垂直反演迭代的方法反演大气成分密度，得到了大量关于临近空间区域大气资料，对长期监测平流层至低热层区域变化提供了可靠的数据支持。利用GOMOS掩星数据，提出一种简单的反演方法——剥洋葱法，反演临近空间高度上臭氧数密度。剥洋葱法假设地球大气对称且水平分层，利用单个波段光谱进行反演，假设在此波长上光谱的大气吸收效应全部由臭氧造成，即选择臭氧吸收占据绝对优势的波长。经分析，在50～100 km高度上可以利用290 nm波段进行反演，在15～50 km高度上可以利用600 nm波段进行反演。根据Beer-Lambert定律，随切点高度自上而下，对恒星光光谱透过率利用剥洋葱法进行反演得到臭氧数密度。将剥洋葱法反演结果与GOMOS官方发布结果相对比，两者符合得很好。
关键词：星光掩星技术；臭氧密度；反演方法；剥洋葱法
Abstract：Stellar occultation technology measures the transmission spectra of light of stars through the atmosphere modified by extinction and refraction and obtain various atmospheric density information by using the absorption differences among components of different wavelengths. While the LEO(Low Earth Orbit) satellite and the star are located on both sides of the earth, the low-orbit satellite receives the transmission spectra at different tangent heights, which constitutes a stellar occultation technology observation. The observed height of the transmission spectra can range from the stratosphere to the low thermosphere, and different bands can be used for the inversion of the density of different atmospheric trace components. Stellar occultation technology has the advantages of multiple detection parameters, global coverage, high vertical resolution, and self-calibration. The Global Ozone Monitoring by Occultation of Stars (GOMOS) instrument onboard the European Space Agency’s ENVISAT satellite measures transmission spectra by stellar occultation technology to detect stratospheric ozone trends. GOMOS is precisely designed and high resolution, operating stably for a decade(2002—2012). With the detection wavelength spanning from ultraviolet to visible light, the spectral inversion and vertical inversion method is used to calculate the atmospheric composition density. GOMOS data provides reliable data support for long-term monitoring of changes from the stratosphere to the lower thermosphere. Using the dataset of GOMOS, this paper proposes a simple inversion method the onion-peeling method to retrieve the ozone density in the near-space region. Under the assumption of symmetrical and layered horizontally atmosphere, the onion-peeling method uses a single band spectrum to inversion, assuming that the atmospheric absorption effect of the spectra at this wavelength is entirely caused by ozone, which means the wavelength at which ozone absorption is chosen to occupy absolute advantage. After analysis and comparison, it is suitable to use the spectra of 290 nm to retrieve the density at the altitude during 50~100 km and the spectral of 600 nm to retrieve the density at the altitude during 15~50 km. According to Beer-Lambert’s law, ozone density is obtained by the onion-peeling method using the stellar transmission spectra from top to bottom at the tangent height. The results of this onion-peeling method are consistent with the results official released results of GOMOS.
Key words：Stellar occultation; Ozone density; Inversion method; Near space
张斯敏，吴小成，孙明晨，胡 雄，宫晓艳. 星光掩星剥洋葱法反演臭氧密度[J]. 光谱学与光谱分析, 2022, 42(01): 203-209.
ZHANG Si-min, WU Xiao-cheng, SUN Ming-chen, HU Xiong, GONG Xiao-yan. Using Onion-Peeling Method to Inverse Ozone Density Based on the Stellar Occultation Technology in the Near Space Region. SPECTROSCOPY AND SPECTRAL ANALYSIS, 2022, 42(01): 203-209.
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