An analytical inversion method for determining regional and global emissions of greenhouse gases: Sensitivity studies and application to halocarbons A. Stohl1, P. Seibert2, J. Arduini3, S. Eckhardt1, P. Fraser4, B. R. Greally5, C. Lunder1, M. Maione3, J. Mühle6, S. O'Doherty5, R. G. Prinn7, S. Reimann8, T. Saito9, N. Schmidbauer1, P. G. Simmonds5, M. K. Vollmer8, R. F. Weiss6, and Y. Yokouchi9 1Norwegian Institute for Air Research, Kjeller, Norway 2Institute of Meteorology, University of Natural Resources and Applied Life Sciences, Vienna, Austria 3University of Urbino, Urbino, Italy 4Centre for Australian Weather and Climate Research, CSIRO Marine and Atmospheric Research, Aspendale, Australia 5School of Chemistry, University of Bristol, Bristol, UK 6Scripps Institute of Oceanography, University of California, San Diego, CA, USA 7Center for Global Change Science, Massachusetts Institute of Technology, Cambridge, MA, USA 8Swiss Federal Laboratories for Materials Testing and Research (Empa), Duebendorf, Switzerland 9National Institute for Environmental Studies, Tsukuba, Japan
Abstract. A new analytical inversion method has been developed to determine the
regional and global emissions of long-lived atmospheric trace gases.
It exploits in situ measurement data from three global networks and
builds on backward simulations with a Lagrangian particle dispersion model.
The emission information is extracted from the observed concentration
increases over a baseline that is itself objectively determined by the inversion algorithm.
The method was applied to two hydrofluorocarbons (HFC-134a, HFC-152a) and
a hydrochlorofluorocarbon (HCFC-22) for the period January 2005 until March 2007.
Detailed sensitivity studies with synthetic as well as with real measurement
data were done to quantify the influence on the results of the a priori emissions
and their uncertainties as well as of the observation and model errors.
It was found that the global a posteriori emissions of HFC-134a, HFC-152a
and HCFC-22 all increased from 2005 to 2006.
Large increases (21%, 16%, 18%, respectively) from 2005 to 2006 were found
for China, whereas the emission changes in North America (−9%, 23%, 17%,
respectively) and Europe (11%, 11%, −4%, respectively) were mostly smaller and less systematic.
For Europe, the a posteriori emissions of HFC-134a and HFC-152a were slightly
higher than the a priori emissions reported to the United Nations Framework
Convention on Climate Change (UNFCCC).
For HCFC-22, the a posteriori emissions for Europe were substantially (by almost
a factor 2) higher than the a priori emissions used, which were based on HCFC
consumption data reported to the United Nations Environment Programme (UNEP).
Combined with the reported strongly decreasing HCFC consumption in Europe,
this suggests a substantial time lag between the reported time of the HCFC-22
consumption and the actual time of the HCFC-22 emission.
Conversely, in China where HCFC consumption is increasing rapidly according to
the UNEP data, the a posteriori emissions are only about 40% of the a priori emissions.
This reveals a substantial storage of HCFC-22 and potential for future emissions in China.
Deficiencies in the geographical distribution of stations measuring halocarbons
in relation to estimating regional emissions are also discussed in the paper.
Applications of the inversion algorithm to other greenhouse gases such as methane,
nitrous oxide or carbon dioxide are foreseen for the future.
Citation: Stohl, A., Seibert, P., Arduini, J., Eckhardt, S., Fraser, P., Greally, B. R., Lunder, C., Maione, M., Mühle, J., O'Doherty, S., Prinn, R. G., Reimann, S., Saito, T., Schmidbauer, N., Simmonds, P. G., Vollmer, M. K., Weiss, R. F., and Yokouchi, Y.: An analytical inversion method for determining regional and global emissions of greenhouse gases: Sensitivity studies and application to halocarbons, Atmos. Chem. Phys., 9, 1597-1620, doi:10.5194/acp-9-1597-2009, 2009.