An analytical inversion method for determining regional and global emissions of greenhouse gases: Sensitivity studies and application to halocarbons

Abstract

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 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 Correspondence to: A. Stohl (ast@nilu.no) 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.

The large contribution of projected HFC emissions to future climate forcing

“…The total consumption of CFCs ϩ HCFCs (in kilotons per year) in developing countries increased by Ϸ8% per year from 1998 to 2007, larger than the mean annual increase in GDP from 1990 to 2010 of 4-6% per year in Asia, Africa and Latin America in the SRES scenarios. These increases in consumption are confirmed by long-term growth and recent acceleration of growth in observed atmospheric mixing ratios of HCFCs (18,19). Recent changes in northern-latitude observations are consistent with less developed country use and more developing country use of HCFCs (18).…”

Global emissions of refrigerants HCFC-22 and HFC-134a: Unforeseen seasonal contributions

“…These so-called "top-down" studies can improve the spatial and temporal distribution of bottom-up inventories and provide insights on the associated emission mechanisms that may be used as information for climate change mitigation. Most recent top-down studies of HCFC-22 and HFC134a indicate lower US emissions and higher emissions in Europe, Australia, and Asia than in the existing inventories (8)(9)(10)(11).…”

Kapitel 2: Emissionen und Konzentrationen strahlungswirksamer atmosphärischer Spurenstoffe

“…Emissionsmodells mit atmosphärischen Transportmodellen, die als "Nebenprodukte" der operationellen Wettervorhersage verstanden werden können (z. B. FLEX-PART, Stohl et al, 2009oder TM5, Krol et al, 2005 lassen sich somit die Verteilungen von Spurenstoffen in der Atmosphäre als Funktion von Raum und Zeit berechnen. Wenn nun Messdaten vorhanden sind, welche die raumzeitliche Variabilität der Spurenstoffe darstellen, können die …”