Observations of 1,1‐difluoroethane (HFC‐152a) at AGAGE and SOGE monitoring stations in 1994–2004 and derived global and regional emission estimates

Abstract

Ground‐based in situ measurements of 1,1‐difluoroethane (HFC‐152a, CH3CHF2) which is regulated under the Kyoto Protocol are reported under the auspices of the AGAGE (Advanced Global Atmospheric Gases Experiment) and SOGE (System of Observation of halogenated Greenhouse gases in Europe) programs. Observations of HFC‐152a at five locations (four European and one Australian) over a 10 year period were recorded. The annual average growth rate of HFC‐152a in the midlatitude Northern Hemisphere has risen from 0.11 ppt/yr to 0.6 ppt/yr from 1994 to 2004. The Southern Hemisphere annual average growth rate has risen from 0.09 ppt/yr to 0.4 ppt/yr from 1998 to 2004. The 2004 average mixing ratio for HFC‐152a was 5.0 ppt and 1.8 ppt in the Northern and Southern hemispheres, respectively. The annual cycle observed for this species in both hemispheres is approximately consistent with measured annual cycles at the same locations in other gases which are destroyed by OH. Yearly global emissions of HFC‐152a from 1994 to 2004 are derived using the global mean HFC‐152a observations and a 12‐box 2‐D model. The global emission of HFC‐152a has risen from 7 Kt/yr to 28 Kt/yr from 1995 to 2004. On the basis of observations of above‐baseline elevations in the HFC‐152a record and a consumption model, regional emission estimates for Europe and Australia are calculated, indicating accelerating emissions from Europe since 2000. The overall European emission in 2004 ranges from 1.5 to 4.0 Kt/year, 5–15% of global emissions for 1,1‐difluoroethane, while the Australian contribution is negligible at 5–10 tonnes/year, <0.05% of global emissions.

Global and regional emissions estimates of 1,1-difluoroethane (HFC-152a, CH&lt;sub&gt;3&lt;/sub&gt;CHF&lt;sub&gt;2&lt;/sub&gt;) from in situ and air archive observations

“…HFC-152a (CH 3 CHF 2 ) is primarily sold as an aerosol and foam-blowing agent (Greally et al, 2007) and as a component of some refrigerant blends (Ashford et al, 2004). Emissions to the atmosphere show both temporal and regional variability depending on the specific application in which HFC-152a is used.…”

Robust extraction of baseline signal of atmospheric trace species using local regression

“…2). It has been shown by Zellweger et al (2009) that the negative trend of CO at Jungfraujoch is the HFC-152a background at Jungfraujoch was higher than at Mace Head, most likely because of the closer proximity of the Jungfraujoch to major source regions (Greally et al, 2007;Reimann et al, 2008). Since about 2008, the HFC152a background concentration at Jungfraujoch has been declining (probably due to stabilizing emissions) and again very close to the background concentration at Mace Head.…”

“…These differences would be of importance when emission estimates are performed using techniques as described e.g. by Reimann et al (2005), and Greally et al (2007) that are based on concentration above background estimates.…”

“…On the other hand, there is a good agreement between the baseline determined with the REBS and the monthly mean background concentrations derived with the AGAGE method, although there are some obvious differences for the measurements at Jungfraujoch after about 2006. The atmospheric lifetime of HFC-152a is about 1.4 yr; degradation of this compound is dominated by reaction with OH (Greally et al, 2007, and references therein). Consequently, it can be expected that HFC-152a is well mixed in the northern hemispheric troposphere and the baselines at Mace Head and Jungfraujoch should be comparable.…”

“…Hence, data filtering is often an essential part of the analysis of data from those sites. For example, data filtering was applied for trend estimations (Thoning et al, 1989;Novelli et al, 1998;Schuepbach et al, 2001;Novelli et al, 2003;Zellweger et al, 2009), for evaluation of source regions and corresponding emission estimates Cox et al, 2005;Reimann et al, 2005;Greally et al, 2007), as well as for modeling of long-range transport of trace gases Balzani Lööv et al, 2008).…”