磁暴等空间天气事件会引起热层中性成分O和N2浓度的显著变化, 故常将氧原子和氮分子的柱密度之比O/N2作为电离层热层受扰动的标志。 研究表明, O和N2柱密度之比O/N2与远紫外气辉OⅠ 135.6 nm和N2 Lyman-Birge-Hopfield(LBH)的柱辐射强度之比135.6/LBH具有很好的相关性, 因此远紫外光学遥感探测对于监测磁暴等空间天气事件显得尤为重要。 自20世纪70年代以来, 国外就开展了远紫外气辉电离层探测的研究工作, 并相继发射了多颗相关卫星, 尤其是美国、 日本以及瑞典等国家。 而我国在轨运行的星载光学遥感探测仪器中, 只有一些工作在微波波段、 可见光波段的载荷, 还没有在远紫外波段工作的遥感探测仪器, 直到2017年11月风云三号D气象卫星的成功发射, 卫星上搭载的电离层光度计是我国首台星载远紫外气辉遥感探测载荷, 它为我们提供了一系列具有自主知识产权的远紫外探测数据, 为开展电离层O/N2特性的研究奠定了基础。 首先阐述了利用柱辐射强度之比135.6/LBH来反演热层中性成分柱密度之比O/N2的理论依据。 其次, 基于MSISE-00大气模型, 利用AURIC来仿真计算135.6/LBH与O/N2之间的比例系数, 然后利用电离层光度计实时观测的远紫外气辉数据来反演电离层O/N2, 进一步验证磁暴期间电离层中性成分受扰动的情况。 在数据处理过程中, 采用了切比雪夫滤波器滤波方式针对数据中的带外杂散光进行了处理, 进一步抑制了杂散光信号对远紫外光谱信号的影响。 最后, 将电离层光度计O/N2的反演结果与国外光学遥感载荷全球紫外成像仪GUVI（Global Ultraviolet Imager）的结果进行对比, 结果显示二者对磁暴的响应一致, O/N2的产品误差RMS约为0.319 6, 文中对造成两者差异的可能原因做出了初步分析, 为后续工作的开展奠定了基础。 此次研究, 首次利用我国自主研发的远紫外气辉遥感探测载荷进行数据反演和分析, 这对我国电离层远紫外遥感探测技术的发展具有重要意义。

Space weather events such as magnetic storms can cause significant changes in the concentration of the neutral components O and N2 in the thermosphere. Therefore, the ratio of the column density of oxygen atom to nitrogen molecule O/N2 is often used as a sign of the ionosphere’s disturbance. The results have shown that the ratio of the density of O and N2 columns density O/N2 and the ratio of the column emission intensity 135.6/LBH of far ultraviolet airglow OⅠ 135.6 nm and N2 LBH have a good correlation, so far ultraviolet optical remote sensing is very important for monitoring space weather. Since the 1970s, research on ionospheric exploration with far ultraviolet airglow has been conducted abroad, and several related satellite coordinates have been launched, especially in the United States, Japan, Sweden and other countries. Among the airborne prediction and optical detection instruments operating in orbit, only some work in the microwave and visible wavelength, and there are no detection instruments working in far ultraviolet longer, until the successful launch of FENGYUN-3D meteorological satellite in November 2017. The ionospheric photometer on the satellite is the first airborne far ultraviolet airglow remote sensing detection load in China. It provides us with a series of far ultraviolet detection data with independent intellectual property rights, and lays a foundation for us to carry out the research of ionospheric O/N2 characteristics. Firstly, we described how to retrieve the ratio of column density O/N2 of the neutral component in the thermosphere by using the ratio of column radiation intensity 135.6/LBH. Secondly, in the msise-00 atmospheric model, the ratio coefficient between 135.6/LBH and O/N2 is calculated by AURIC, and then the ionospheric O/N2 is retrieved by using the far ultraviolet airglow data observed by ionospheric photometer in real time, which further verifies the disturbance of the ionospheric neutral component during the magnetic storm. In the process of data processing, Chebyshev filter is used to process the out of band stray light in the data, which further suppresses the influence of the stray light signal on the FUV spectrum signal. Finally, the inversion results of O/N2 retrieved by Ionospheric Photometer are compared with the results of Global Ultraviolet Imager (GUVI) loaded by foreign optical remote sensing. The results show that they have the same response to a magnetic storm, and the product RMS error of O/N2 is about 0.319 6. In this paper, we have made an initial analysis of the possible causes of the differences, which lays a foundation for the follow-up work. This studyis the first time to use the data of the far ultraviolet airglow remote sensing payload independently developed in China for data inversion and analysis, which is of great significance to the development of the ionospheric far ultraviolet remote sensing technology in China.