Global and regional emission estimates for HCFC-22

E. Saikawa, M. Rigby, R. G. Prinn, S. A. Montzka, B. R. Miller, L. J. M. Kuijpers, P. J. B. Fraser, M. K. Vollmer, T. Saito, Y. Yokouchi, C. M. Harth, J. Muehle, R. F. Weiss, P. K. Salameh, J. Kim, S. Li, S. Park, K. -R. Kim, D. Young, S. O'DohertyA. McCulloch, P. B. Krummel, C. Lunder, O. Hermansen, M. Maione, J. Arduini, B. Yao, L. X. Zhou, H. J. Wang, J. W. Elkins, B. Hall

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Abstract

HCFC-22 (CHClF2, chlorodifluoromethane) is an ozone-depleting substance (ODS) as well as a significant greenhouse gas (GHG). HCFC-22 has been used widely as a refrigerant fluid in cooling and air-conditioning equipment since the 1960s, and it has also served as a traditional substitute for some chlorofluorocarbons (CFCs) controlled under the Montreal Protocol. A low frequency record on tropospheric HCFC-22 since the late 1970s is available from measurements of the Southern Hemisphere Cape Grim Air Archive (CGAA) and a few Northern Hemisphere air samples (mostly from Trinidad Head) using the Advanced Global Atmospheric Gases Experiment (AGAGE) instrumentation and calibrations. Since the 1990s high-frequency, high-precision, in situ HCFC-22 measurements have been collected at these AGAGE stations. Since 1992, the Global Monitoring Division of the National Oceanic and Atmospheric Administration/Earth System Research Laboratory (NOAA/ESRL) has also collected flasks on a weekly basis from remote sites across the globe and analyzed them for a suite of halocarbons including HCFC-22. Additionally, since 2006 flasks have been collected approximately daily at a number of tower sites across the US and analyzed for halocarbons and other gases at NOAA. All results show an increase in the atmospheric mole fractions of HCFC-22, and recent data show a growth rate of approximately 4% per year, resulting in an increase in the background atmospheric mole fraction by a factor of 1.7 from 1995 to 2009. Using data on HCFC-22 consumption submitted to the United Nations Environment Programme (UNEP), as well as existing bottom-up emission estimates, we first create globally-gridded a priori HCFC-22 emissions over the 15 yr since 1995. We then use the three-dimensional chemical transport model, Model for Ozone and Related Chemical Tracers version 4 (MOZART v4), and a Bayesian inverse method to estimate global as well as regional annual emissions. Our inversion indicates that the global HCFC-22 emissions have an increasing trend between 1995 and 2009. We further find a surge in HCFC-22 emissions between 2005 and 2009 from developing countries in Asia - the largest emitting region including China and India. Globally, substantial emissions continue despite production and consumption being phased out in developed countries currently.

Original languageEnglish
Pages (from-to)10033-10050
Number of pages18
JournalAtmospheric Chemistry and Physics
Volume12
Issue number21
DOIs
Publication statusPublished - 1 Nov 2012

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