The first remote-sensing measurements of HFC-32 in the Earth's atmosphere by the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS)

Atmospheric hydrofluorocarbon (HFC) abundances are increasing rapidly because of the Montreal Protocol phase-out of the production and consumption of chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs). HFC-32 (CH2F2, difluoromethane) mole fractions (volume mixing ratios, VMRs) have been retrieved from infrared absorption spectra recorded from orbit with the Atmospheric Chemistry Experiment Fourier transform spectrometer (ACE-FTS) between 2004 and 2020. Global altitude-latitude distributions have been determined from the ACE-FTS VMR altitude profiles. The HFC-32 VMR time series have been computed and compared with values obtained from in situ flask measurements made by the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory. HFC-32 abundances are increasing exponentially.