The recovery of the stratospheric ozone layer relies on the continued decline in the atmospheric concentrations of ozone-depleting gases such as the chlorofluorocarbons 1. The atmospheric concentration of trichlorofluoromethane (CFC-11), the second most abundant chlorofluorocarbon, has declined substantially since the mid-1990s 2. A recently reported slowdown in the decline of the atmospheric concentration of CFC-11 after 2012, however, implies that global emissions have increased 3,4. A concurrent increase in CFC-11 emissions from eastern Asia contributes to the global emission increase, but the location and magnitude of this regional source remain uncertain 3. Here we use high-frequency atmospheric observations from Gosan, Republic of Korea and Hateruma, Japan, together with global monitoring data and atmospheric chemical transport model simulations to investigate regional CFC-11 emissions from eastern Asia. We find that emissions from eastern mainland China are 7.0 ± 3.0 Gg yr-1 higher in 2014-2017 compared to 2008-2012, and the emissions increase arises primarily around the northeastern provinces of Shandong and Hebei. This increase accounts for a substantial fraction (about 40-60%, or more) of the global CFC-11 emission rise. We find no evidence for a significant increase in emissions from any other eastern Asian countries or other regions of the world where available data allow for the detection of regional emissions. Attribution of any remaining fraction of the global CFC-11 emission rise to other regions is limited by the sparsity of long-term measurements of sufficient frequency near potentially emissive regions. Multiple considerations suggest that the increase in CFC-11 emissions from eastern mainland China is likely the result of new Energy & Industrial Strategy (BEIS, UK, formerly the Department of Energy and Climate Change (DECC)) contract 1028/06/2015 to the University of Bristol and the UK Meteorological Office. Ragged Point, Barbados is supported by the National Oceanic and Atmospheric Administration (NOAA, USA), contract RA-133-R15-CN-0008 to the University of Bristol. L.W., M.L.

Carbon tetrachloride (CCl 4 ) is an ozone-depleting substance, accounting for about 10% of the chlorine in the troposphere. Under the terms of the Montreal Protocol, its production for dispersive uses was banned from 2010. In this work we show that, despite the controls on production being introduced, CCl 4 emissions from the eastern part of China did not decline between 2009 and 2016. This finding is in contrast to a recent bottom-up estimate, which predicted a significant decrease in emissions after the introduction of production controls. We find eastern Asian emissions of CCl 4 to be 16 (9-24) Gg/year on average between 2009 and 2016, with the primary source regions being in eastern China. The spatial distribution of emissions that we derive suggests that the source distribution of CCl 4 in China changed during the 8-year study period, indicating a new source or sources of emissions from China's Shandong province after 2012. Plain Language Summary Carbon tetrachloride is one of several man-made gases that contributeto the depletion of the ozone layer high in the atmosphere. Because of this, restrictions were introduced on the use of this ozone-depleting substance, with the expectation that production should by now be close to 0. However, the slower than expected rate of decline of carbon tetrachloride in the atmosphere shows this is not the case, and a large portion of global emissions are unaccounted for. In this study we use atmospheric measurements of carbon tetrachloride from a site in East Asia to identify the magnitude and location of emissions from this region between 2009 and 2016. We find that there are significant ongoing emissions from eastern China and that these account for a large part of the missing emissions from global estimates. The presence of continued sources of this important ozone-depleting substance indicates that more could be done to speed up the recovery of the ozone layer.

Abstract. High frequency, in situ observations from 11 globally distributed sites for the period 1994-2014 and archived air measurements dating from 1978 onward have been used to determine the global growth rate of 1,1-difluoroethane (HFC-152a, CH 3 CHF 2 ). These observations have been combined with a range of atmospheric transport models to derive global emission estimates in a topdown approach.

The East Asian Summer Monsoon driven by temperature and moisture gradients between the Asian continent and the Pacific Ocean, leads to approximately 50% of the annual rainfall in the region across 20–40°N. Due to its increasing scientific and social importance, there have been several previous studies on identification of moisture sources for summer monsoon rainfall over East Asia mainly using Lagrangian or Eulerian atmospheric water vapor models. The major source regions for EASM previously proposed include the North Indian Ocean, South China Sea and North western Pacific. Based on high-precision and high-frequency 6-year measurement records of hydrofluorocarbons (HFCs), here we report a direct evidence of rapid intrusion of warm and moist tropical air mass from the Southern Hemisphere (SH) reaching within a couple of days up to 33°N into East Asia. We further suggest that the combination of direct chemical tracer record and a back-trajectory model with physical meteorological variables helps pave the way to identify moisture sources for monsoon rainfall. A case study for Gosan station (33.25°N, 126.19°E) indicates that the meridional transport of precipitable water from the SH accompanying the southerly/southwesterly flow contributes most significantly to its summer rainfall.