Investigating CFC-11 Emissions and Their Changes Using Results from the Hippo and ATom Atmosphere Sampling Surveys

We recently determined that emissions of trichlorofluoromethane (CFC-11) increased after 2012 by 13 ± 5 Gg/yr (or 25 ± 13 %) despite a reported phase out of production since 2010 (doi.org/10.1038/s41586-018-0106-2). Some portion of the detected emission increase was attributable to eastern Asia, and a second paper confirmed those results and further indicated that at least 40 to 60% of the global emission increase was attributable to eastern China (doi.org/10.1038/s41586-019-1193-4). Unfortunately, regions responsible for the balance of the emission increase have yet to be identified. The extensive air sampling conducted throughout the Pacific Ocean basin during HIAPER Pole-to-Pole (HIPPO) and throughout the Pacific and Atlantic Ocean basins during the Atmospheric Tomography Mission (ATom) provide additional information to address this issue. Results from these projects are potentially valuable for addressing this issue because they span the years over which emissions of CFC-11 increased (before and after 2012), and they sampled air in regions downwind of multiple continents. In this work, we will discuss results from an inverse analysis of the data from these sampling programs to address this issue. Observations obtained from other platform during the same periods as the HIPPO and ATom missions will also be considered, such as those made on an ongoing basis from NOAA ground-based and aircraft profiling sites.