Global and regional emissions of HFC‐125 (CHF₂CF₃) from in situ and air archive atmospheric observations at AGAGE and SOGE observatories

Abstract

High‐frequency, in situ observations from the Advanced Global Atmospheric Gases Experiment (AGAGE) and System for Observation of halogenated Greenhouse gases in Europe (SOGE) networks for the period 1998 to 2008, combined with archive flask measurements dating back to 1978, have been used to capture the rapid growth of HFC‐125 (CHF2CF3) in the atmosphere. HFC‐125 is the fifth most abundant HFC, and it currently makes the third largest contribution of the HFCs to atmospheric radiative forcing. At the beginning of 2008 the global average was 5.6 ppt in the lower troposphere and the growth rate was 16% yr−1. The extensive observations have been combined with a range of modeling techniques to derive global emission estimates in a top‐down approach. It is estimated that 21 kt were emitted globally in 2007, and the emissions are estimated to have increased 15% yr−1 since 2000. These estimates agree within approximately 20% with values reported to the United Nations Framework Convention on Climate Change (UNFCCC) provided that estimated emissions from East Asia are included. Observations of regionally polluted air masses at individual AGAGE sites have been used to produce emission estimates for Europe (the EU‐15 countries), the United States, and Australia. Comparisons between these top‐down estimates and bottom‐up estimates based on reports by individual countries to the UNFCCC show a range of approximately four in the differences. This process of independent verification of emissions, and an understanding of the differences, is vital for assessing the effectiveness of international treaties, such as the Kyoto Protocol.

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

“…At Cape Grim an additional source of seasonality is due to seasonally varying transport between the NH and SH, which is generally in phase with the sink induced seasonal cycle. This competition between OH summertime loss and seasonally varying transport has been observed at many other AGAGE locations (Prinn et al, 1992;Greally et al, 2007;O'Doherty et al, 2009O'Doherty et al, , 2014Li et al, 2011). Figure 6 shows the mole fractions output from the AGAGE global 12-box model, along with the monthly mean semihemispheric average observations used in the inversion.…”

“…The estimated accuracy of the calibration scale for HFC152a is 4 %: a more detailed discussion of the measurement technique and calibration procedure is reported elsewhere (Miller et al, 2008;O'Doherty et al, 2009;Mühle et al, 2010). HFC-152a was determined using the MS in selected ion monitoring mode (SIM) with a target ion CH 3 CF + 2 (m/z 65) and qualifier ion CH 3 CF + (m/z 46).…”

Recent increases in the atmospheric growth rate and emissions of HFC-23 (CHF<sub>3</sub>) and the link to HCFC-22 (CHClF<sub>2</sub>) production

“…The estimated accuracies of the calibration scales for HFC-23 and HCFC-22 are discussed below and a more detailed discussion of the measurement techniques and calibration procedures are reported elsewhere (Miller et al, 2008;O'Doherty et al, 2009;Mühle et al, 2010). HFC-23 and HCFC-22 measurements from all AGAGE sites are reported relative to the SIO-07 and SIO-05 primary calibration scales respectively, which are defined by suites of standard gases prepared by diluting gravimetrically prepared analyte mixtures in N 2 O to near-ambient levels in synthetic air (Prinn et al, 2000;Miller et al, 2008).…”

Abundance and Sources of Atmospheric Halocarbons in the Eastern Mediterranean

“…HFC-134a is currently the preferred refrigerant in mobile air conditioning systems and, together with HFC-125, which is mostly used in refrigerant blends for residential and commercial re-645 frigeration, belongs to the two most popular HFCs in Europe O'Doherty, et al, 2009;Velders, et al, 2009;Xiang, et al, 2014]. This is reflected by the large amplitude and frequency of pollution peaks, which were observed at all continuous observa- …”