Assessment of Retrieved N₂O, NO₂, and HF Profiles from the Atmospheric Infrared Ultraspectral Sounder Based on Simulated Spectra.
Assessment of Retrieved N₂O, NO₂, and HF Profiles from the Atmospheric Infrared Ultraspectral Sounder Based on Simulated Spectra.
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基于模拟光谱的大气红外超光谱探测仪反演 N2O、NO2 和 HF 剖面的评估。
DOI：
10.3390/s18072209
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发表时间：
2018-07-09
期刊：
影响因子：
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通讯作者：
Si Y
中科院分区：
文献类型：
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作者：
Wang H;Li X;Xu J;Zhang X;Ge S;Chen L;Wang Y;Zhu S;Miao J;Si Y
大气红外超谱探测仪是第一台搭载在GF5上的高分辨率(0.02厘米−1)太阳掩星探测仪，于2018年5月由中国发射升空。然而，直到半年后，才根据其业务数据对大气成分垂直剖面进行了相关研究。由于Hin轨道测试的迫切需要，用参考正演模型(RFM)加上不同高度的不同随机噪声计算的模拟谱来代替真实谱(以下称为参考谱)。在N2O、NO2和HF物种的参考光谱的生成过程中，ACE-FTS(SCISAT卫星上的大气化学实验-傅里叶变换光谱仪)二级产品取代了大气背景剖面中包含的相应剖面。采用最优估计法提取大气中的N2O、NO2和HF剖面。将反演结果与ACE-FTS Level 2产品进行比较，计算了这三个物种的相对偏差。对于N2O，平均相对偏差在25公里以下小于6%，而在25-45公里范围内偏差较大，最大值在25%左右。此外，在20-45公里范围内，NO2的差异小于5%，其中20公里以下和45公里以上的差异较大，最大偏差达到±40%。对于HF，对于所有的切线高度，相对偏差小于6%，这意味着满意的恢复。用垂直分辨率、平均核和自由度数对算法进行了评估，结果表明，所提取的信息量更多地归因于参考光谱的贡献，而不是先验分布。最后，在北极区、中纬度北部、热带、中纬度南部和南极地区对N2O、NO2和HF进行了大量的反演试验，得到了可靠的结果。因此，在很大程度上，AIUS系统采用的算法能够可靠、准确地处理检索。
The Atmospheric Infrared Ultraspectral Sounder (AIUS), the first high-resolution (0.02 cm−1) solar occultation sounder, aboard GF5, was launched in May 2018 from China. However, relevant studies about vertical profiles of atmospheric constituents based on its operational data were not conducted until half a year later. Due to an urgent need for Hin-orbit tests, the real spectra (called reference spectra hereafter) were substituted with simulated spectra calculated from the reference forward model (RFM) plus different random noises at different altitudes. In the generation process of the reference spectra for N2O, NO2, and HF species, ACE-FTS (Atmospheric Chemistry Experiment–Fourier Transform Spectrometer instrument on the SCISAT satellite) level 2 products replace corresponding profiles included in the atmospheric background profiles. The optimal estimation method is employed to extract N2O, NO2, and HF profiles in this study. Comparing the retrieved results with ACE-FTS level 2 products, the relative deviations for these three species are calculated. For N2O, the average relative deviation is less than 6% at altitudes below 25 km, while larger deviations are observed in the range of 25–45 km, with the maximum being at ~25%. Additionally, the difference for NO2 is less than 5% in the 20–45 km range, with a larger discrepancy found below 20 km and above 45 km; the maximum deviation reaches ±40%. For HF, the relative deviation is less than 6% for all tangent heights, implying satisfactory retrieval. The vertical resolution, averaging kernel, and number of degrees of freedom are used to assess the retrieval algorithm, which indicate that the retrieved information content is much more attributable to the reference spectra contribution than to the a priori profile. Finally, a large number of retrieval tests are performed for N2O, NO2, and HF in selected areas covering the Arctic region, northern middle latitude, tropics, southern middle latitude, and Antarctic region, and reliable results are obtained. Thus, to a great extent, the algorithm adopted in the AIUS system can process retrievals reliably and precisely.