Atmospheric Chemistry Experiment Fourier Transform Spectrometer Level 2 Data v2.2

The Atmospheric Chemistry Experiment (ACE) is a Canadian satellite mission for remote sensing of the Earth's atmosphere that was launched into a high-inclination (74°), circular low-earth (650 km from the surface) orbit on August 12, 2003 (Bernath et al., 2006). This orbit gives SCISAT coverage of tropical, mid-latitude, and polar regions, ranging from latitudes 85N to 85S, allowing it to study a range of atmospheric processes. The main goal of ACE is to study the atmospheric chemistry and dynamics that affect stratospheric ozone depletion in the Arctic, but ACE measurements are also being used to study ozone depletion in the Antarctic, the relationship between chemistry and climate change, the atmospheric effects of biomass burning, the effects of aerosols and clouds on the global energy balance, and many other areas of atmospheric science. The primary instrument on ACE, a high-resolution Fourier Transform Spectrometer (FTS), is used in solar occultation mode to determine vertical profiles of trace gas volume mixing ratios (VMRs) and temperature. The ACE-FTS records a measurement every 2s, corresponding to a typical altitude spacing of 2-6 km. On the ground at the University of Waterloo, the retrieved results are interpolated onto a 1 km “grid” using a piecewise quadratic method. Included in this data set are ascii files for each "occultation", on both the "retrieval", or "measurement" grid ("tangrid") and the "scientific", 1 km grid, cataloged using the naming conventions "sr*****" and "ss*****" for sunrises and sunsets, respectively. Further, there is an additional pair of files for each occultation event for less abundant, subsidiary isotopologues (marked "sx*****iso.asc, etc.). All files contain a short header, followed by a series of columns with VMRs for each molecule. More detailed information can be accessed in the two attached documents, "ACEFTSPublicReleaseDocumentation.pdf", which includes background and supporting material to best make use of the data, and "ACE-SOC-0011-1D-ACE-FTS_ascii_fileformat_for_v2.2.pdf", with general comments on the file and data formatting itself. All retrieved molecules and their VMRs are presented in the ace_v2.2_asc.zip file, except for three species that were fixed and released shortly afterward. Data for ozone (O3), HDO, and N2O5 can be found in separate zip files, named according to the molecule they contain. Heavy water, HDO, is presented alongside all other isotopologues, while O3 and N2O5 are provided in a single, unique column.

大气化学实验（Atmospheric Chemistry Experiment，ACE）是一项加拿大卫星任务，旨在对地球大气进行遥感观测，于2003年8月12日发射进入高倾角（74°）圆形近地轨道（距地表650公里）（Bernath等人，2006）。该轨道使SCISAT卫星能够覆盖热带、中纬度和极地地区（纬度范围85°N至85°S），从而得以研究多种大气过程。ACE的主要目标是研究影响北极平流层臭氧损耗（stratospheric ozone depletion）的大气化学与动力学（atmospheric chemistry and dynamics），但ACE的观测数据也被用于研究南极臭氧损耗、化学与气候变化的关系、生物质燃烧（biomass burning）对大气的影响、气溶胶与云（aerosol and cloud）对全球能量平衡（global energy balance）的影响，以及大气科学的其他诸多领域。
ACE的核心仪器是高分辨率傅里叶变换光谱仪（Fourier Transform Spectrometer，FTS），其采用太阳掩星模式（solar occultation mode）测定痕量气体体积混合比（Volume Mixing Ratio，VMR）的垂直廓线及温度。ACE-FTS每2秒记录一次测量数据，对应典型高度间隔为2-6公里。滑铁卢大学地面站采用分段二次方法将反演结果插值至1公里“网格”上。
本数据集包含每个掩星事件（occultation）的ASCII文件，分别对应“反演网格”（retrieval grid）或“测量网格”（tangrid，即measurement grid）以及“科学1公里网格”；日出与日落事件的文件分别按“sr*****”和“ss*****”的命名规范分类。此外，每个掩星事件另有一对额外文件，用于记录含量较低的次要同位素体（isotopologue），标记为“sx*****iso.asc”等。所有文件均含简短头信息，后续为一系列列数据，列中展示各分子的VMR值。
更详细信息可查阅两份附件文档：《ACEFTSPublicReleaseDocumentation.pdf》（含背景及支持材料，助力数据最佳利用）和《ACE-SOC-0011-1D-ACE-FTS_ascii_fileformat_for_v2.2.pdf》（含文件与数据格式的通用说明）。所有反演得到的分子及其VMR均收录于ace_v2.2_asc.zip文件中，但三种后续固定并发布的物种除外。臭氧（O₃）、HDO和N₂O₅的数据可在单独的zip文件中获取，文件名按所含分子命名。重水（HDO）与其他所有同位素体一同呈现，而O₃和N₂O₅则单独列于唯一列中。