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Abstract:
Hydrochlorofluorocarbon HCFC-133a (CF3CH2Cl) is an anthropogenic
compound whose consumption for emissive use is restricted under the
Montreal Protocol. A recent study showed rapidly increasing atmospheric
abundances and emissions. We report that, following this rise, the
atmospheric abundance and emissions have declined sharply in the past
three years. We find a Northern Hemisphere HCFC-133a increase from 0.13
ppt (dry-air mole fraction in parts per trillion) in 2000 to 0.50ppt in
2012-mid-2013 followed by an abrupt drop to similar to 0.44 ppt by early
2015. Global emissions derived from these observations peaked at 3.1kt
in 2011, followed by a rapid decline of similar to 0.5 ktyr(-2) to reach
1.5 ktyr(-1) in 2014. Sporadic HCFC-133a pollution events are detected
in Europe from our high-resolution HCFC-133a records at three European
stations, and in Asia from samples collected in Taiwan. European
emissions are estimated to be <0.1 ktyr(-1) although emission hot spots
were identified in France.
