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

Abstract

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 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.