Atmospheric Chemistry Experiment SciSat Level 2 Processed Data, v4.1/v4.2

The Atmospheric Chemistry Experiment is a satellite-based mission that has been probing the Earth's atmosphere via solar occultation since February 2004. The solar occultation approach provides global coverage over the order of a few months, with up to 30 occultations over limited latitude ranges on a given day. Instruments on board include a high-resolution Fourier transform spectrometer (ACE-FTS) measuring in the infrared (750-4400 cm-1) and a pair of filtered imagers operating at 1.02 and 0.525 µm. Level 2 data on a 1-km altitude grid from ACE-FTS processing version v4.1/4.2, spanning February 2004 to July 2024, are provided in this data set. This processing version added seven new molecules and three new subsidiary isotopologues compared to v3.5/3.6, for a total of 44 molecules and 24 isotopologues. V4.1/4.2 fixed problems encountered from saturation of CO2 lines in the pressure-temperature retrieval in v4.0, along with removing spikes that occurred in v4.0 in the presence of polar stratospheric clouds. For the imagers, forward model calculations were changed to a 100 m altitude grid (rather than a 1 km grid) in version 4 processing. ACE SciSat Level 2 Processed Data, v4.1/4.2. Temperature, Pressure and Volume Mixing Ratio (VMR) profiles as a function of altitude for many atmospherically relevant molecules: H2O, O3, N2O, CO, CH4, NO, NO2, HNO3, HF, HCl, OCS, N2O5, ClONO2, HCN, CH3Cl, CF4, CFC-12 (CCl2F2), CFC-11 (CCl3F), COF2, COCl2, COClF, C2H6, C2H2, HCFC-22 (CHClF2), HCOOH, SF6, HO2NO2, H2O2, H2CO, CH3OH, CCl4, N2, O2, CFC-113 (Cl2FC-CClF2), HCFC-141b (Cl2FC-CH3), HCFC-142b (ClF2C-CH3), HFC-134a (F3C-CFH2), PAN (CH3C(O)OONO2), CHF3, acetone (C3H6O), SO2, CH3CN, ClO, CO2, as well as isotopologues for some of these molecules. Imager (IMG) and geolocation (GLC) data are also included. C. Boone, et al. Version 4 retrievals for the atmospheric chemistry experiment Fourier transform spectrometer (ACE-FTS) and imagers, 106939, 2020; doi:10.1016/j.jqsrt.2020.106939.