Trends in atmospheric composition between 2004–2023 using version 5 ACE-FTS data

The Atmospheric Chemistry Experiment (ACE) is a satellite mission that has been in orbit since 2003. The primary instrument on ACE is a Fourier transform spectrometer (FTS) that records infrared atmospheric transmittance spectra in the limb geometry using the Sun as a light source. Version 5 of ACE-FTS data processing contains improved volume mixing ratio (VMR) profiles for 46 molecules and 24 isotopologues, including HFC-32 (CH2F2) and HOCl as new routine data products. VMR trends for each of the 46 molecules are reported for regions of atmospheric interest. Specifically, the longevity of the ACE mission has provided an opportunity to monitor the effectiveness of the Montreal Protocol on Substances that Deplete the Ozone Layer. It is observed that chlorofluorocarbons (CFCs) are declining, hydrochlorofluorocarbons (HCFCs) are no longer increasing, but hydrofluorocarbons (HFCs) are still increasing rapidly. Greenhouse gases such as carbon dioxide are also monitored and comparisons with National Oceanic and Atmospheric Administration (NOAA) and Advanced Global Atmospheric Gases Experiment (AGAGE) measurements are made.