Observations of High Levels of Ozone-Depleting CFC-11 at a Remote Mountain-Top Site in Southern China

Lin, Youjing; Gong, Daocheng; Lv, Shaojun; Ding, Yaozhou; Wu, Gengchen; Wang, Hao; Li, Yanlei; Wang, Yujin; Zhou, Lei; Wang, Boguang

doi:10.1021/acs.estlett.9b00022

Cited by 22 publications

(17 citation statements)

References 36 publications

(45 reference statements)

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“…Rigby et al (2019) discovered an increase of CFC‐11 emissions primarily around the northeastern provinces of Shandong and Hebei in China. Lin et al (2019) reported findings from a field campaign carried out in 2017 that the CFC‐11 concentration in southwestern and central China then was higher than the background measurements in East Asia and the northern hemisphere. All these discoveries were based on surface in situ observations, which cannot provide the global, or at least near‐global, spatial patterns of the trends.…”

Section: Introductionmentioning

confidence: 99%

Near‐Global CFC‐11 Trends as Observed by Atmospheric Infrared Sounder From 2003 to 2018

2020

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Recent studies have indicated a slowdown of the decline of CFC-11 concentration since 2012. Ground-based observations used in such studies have their limitations in terms of global coverage. Here we show that the CFC-11 time-varying behaviors can be seen by double differencing nadir-view, clear-sky brightness temperatures of four AIRS (Atmospheric Infrared Sounder) channels in an infrared CFC-11 absorption band. Assuming that CFC-11 is vertically well mixed through the troposphere, we retrieve CFC-11 surface concentration and its secular trend using such AIRS observations over the near globe (55°S to 55°N) from January 2003 to December 2018. The retrieved trends of CFC-11 at the 11 ground sites agree well with the trends derived from in situ measurements at those sites. Our results show that, from 55°S to 55°N, the CFC-11 trends from January 2003 to December 2012 are all negative, ranging from −2.5 to −1 ppt/year. The trends from January 2003 to December 2018 are less negative by as much as 0.5-1 ppt/year over the Shandong peninsula, the Arabian Peninsula, and north India and Nepal area, and such differences in the trends are statistically significant. Factors other than the CFC-11 that can affect the retrievals and trends are also discussed. These findings can help us depict the near-global spatial distribution of the CFC-11 trends from 2003 to 2018. The analysis described here has the potential to be used with current and future hyperspectral sounders to help monitor the CFC-11 from space.

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Section: Introductionmentioning

confidence: 99%

Near‐Global CFC‐11 Trends as Observed by Atmospheric Infrared Sounder From 2003 to 2018

2020

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“…Moreover, recent measurements and modelling studies pointed to a significant increase in CFC-11 emissions in East Asia and especially in Eastern China, including Shandong and Hebei provinces [4,14,15]. Later on, a high level of CFC-11, about 30 pptv above the global background values, was observed in China [16,17], which further indicated its unexpected emissions in some regions.…”

Section: Introductionmentioning

confidence: 99%

Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China

Zhen

Yang

Zhou³

et al. 2020

Atmosphere

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Recent studies have indicated that Eastern China might be a potential source region of increased atmospheric chlorofluorocarbons (CFCs). To investigate this possibility, a field measurement was carried out from October to December 2017 for identifying the ambient concentration levels of representative trichlorofluoromethane (CFC-11), dichlorodifluoromethane (CFC-12), trifluorotrichloroethane (CFC-113), and tetrafluorodichloroethane (CFC-114) at the residential and municipal solid waste (MSW) landfills and industrial sites in Eastern China. The ambient mixing ratios of CFCs at residential sites were almost within 20% enhancement of the global background sites. The highest levels of CFCs were observed at the MSW landfill sites. Moreover, CFC-11 and CFC-113 concentrations at MSW landfills, which were in service, were two times higher than that at completed MSW landfills. Mean concentrations of 322 pptv for CFC-11, 791 pptv for CFC-12, 91 pptv for CFC-113, and 16 pptv for CFC-114 at various industrial sites were higher than that at residential sites, but they were obviously lower than that at MSW landfills in use. A poor intercorrelation between the CFCs indicated that they did not come from the same sources. Higher concentrations measured in this study compared with background sites indicates that MSW landfills could be an unintentional emission source and there are still substantial amounts of CFCs being stored in banks that may discharge CFCs into the atmosphere in Eastern China.

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“…Here, n ij is the total number of endpoints that fall in the ijth cell (Figure S2) and m ij is the number of endpoints for which measured values exceed a specified criterion value in the ijth cell. Previous studies used the mean (Hui et al, 2019;Lin et al, 2019), 50th percentile (Li, Ye, et al, 2016;Polissar et al, 1999), 75th percentile (N. Gao et al, 2012;M. Yang et al, 2021;Zhao et al, 2015), and 90th percentile Fang et al, 2018) as criterion values.…”

Section: Trajectories Clustering and Potential Source Contribution Functionmentioning

confidence: 99%

“…The results of this work expand upon earlier studies locating the origin of CFC-11 emissions. Also applying the PSCF technique, Lin et al (2019) documented that high levels of CFC-11 observed in Nanjing, China in October 2017 originated from less developed regions in southwestern and central China, with a minor fraction emerging from the PRD metropolitan region. M. Yang et al (2021) also used the PSCF method to find high CFC-11 mixing ratios observed from June 2017-April 2018 at Mount Tai (located in Shandong Province) had traveled from Shanxi, Hebei, Anhui, and Henan provinces.…”

Section: Potential Emission Source Regionsmentioning

confidence: 99%

Airborne Observations of CFCs Over Hebei Province, China in Spring 2016

et al. 2021

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The discovery of the Antarctic ozone hole prompted international action to reduce production, trade, and emissions of chlorofluorocarbons (CFCs) and other ozone depleting substances (ODSs), first introduced as nontoxic and nonflammable refrigerants in the 1930s (Midgley, 1937). The resulting efforts, the Montreal Protocol on Substances That Deplete the Ozone Layer (hereafter, the Montreal Protocol) and subsequent amendments, are responsible for decreases in atmospheric abundances of ODSs since the 1990s (Cunnold et al., 1997) and the start of the recovery of the ozone layer (WMO, 2018). In addition to contributing to

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Observations of High Levels of Ozone-Depleting CFC-11 at a Remote Mountain-Top Site in Southern China

Cited by 22 publications

References 36 publications

Near‐Global CFC‐11 Trends as Observed by Atmospheric Infrared Sounder From 2003 to 2018

Near‐Global CFC‐11 Trends as Observed by Atmospheric Infrared Sounder From 2003 to 2018

Monitoring Chlorofluorocarbons in Potential Source Regions in Eastern China

Airborne Observations of CFCs Over Hebei Province, China in Spring 2016

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