250 likes | 370 Views
Evaluation of CO and SF 6 as quantitative tracers for fossil fuel CO 2 : The Experimentalists’ view. Ingeborg Levin 1 , Ute Karstens 2 , Ulrike Gamnitzer 1 , Christoph Schönherr 1 , Bernd Kromer 1 and Samuel Hammer 1 1 Institut für Umweltphysik Universität Heidelberg
E N D
Evaluation of CO and SF6 as quantitative tracers for fossil fuel CO2:The Experimentalists’ view Ingeborg Levin1,Ute Karstens2, Ulrike Gamnitzer1,Christoph Schönherr1, Bernd Kromer1and Samuel Hammer1 1Institut für Umweltphysik Universität Heidelberg 2Max-Planck-Institut für Biogeochemie, Jena
February CO2 Fluxes Fossil fuel CO2 (EDGAR V3.2 FT, Olivier et al., 2005) Biome-BGC NEE (Churkina et al., 2003) 10-9 kg C m-2 s-1 -10 0 10 20 30 40 50
Can we validate these model results ? … measure total CO2 and fossil fuel CO2
—› measure Radiocarbon (14C) in atmospheric CO2 … … because fossil fuel CO2 contains no 14C and dilutes atmospheric 14CO2
Long-term 14CO2 background observations in Europe „clean“ D14CO2 background level in the Alps Reference: Atmosphere in 1890
Long-term 14CO2 observations in Europe „clean“ D14CO2 background level in the Alps Depletion of the D14CO2 level close to fossil fuel sources
Monthly mean fossil fuel CO2 at Schauinsland station and in Heidelberg mean fossil fuel CO2 offset: Schauinsland: ca. 1.4 ppm Heidelberg: ca. 10 ppm
… but the temporal resolution of our 14C measurements is poor: weekly means … and the sensitivity is quite low: minimum uncertainty ≈ ±2.5 ‰ of 370 ppm ≥ ±1 ppm
—›proxies/surrogates needed to substitute 14CO2 observations Carbon Monoxide (CO) Sulfur Hexafluoride (SF6)
Continuous trace gas observations in Heidelberg in October 2004 CO: Mainly anthropogenic sources (fossil fuel burning) and oxidation of hydrocarbons chemical life time ca. 2 months SF6: Only anthropogenic sources roughly distributed according to population density chemically inert CO2 CO SF6
How well can we quantitatively use CO as a fossil fuel CO2 surrogate ?
Fossil fuel CO2 and CO offset and their ratio Weighted mean ratio [ppb/ppm]: Observations: 12.2±0.4
Fossil fuel CO2 and CO offset and their ratio in comparison with emissions inventories Weighted mean ratios [ppb/ppm]: Observations: 12.2±0.4 Emissions Inventories (incl. soils, etc.) Edgar: 14.7
Fossil fuel CO2 and CO offset and their ratio in comparison with emissions inventories Weighted mean ratios [ppb/ppm]: Observations: 12.2±0.4 Emissions Inventories (incl. soils, etc.) IER: 18.0 Edgar: 14.7 IER: Institute of Energy Economics and Rational Use of Energy, Stuttgart
Conclusions (I): • Fossil fuel CO2 (FFCO2) emissions in Europe contribute almost half to the continental CO2 signal • Monthly mean fossil fuel CO2 levels at urban sites can be determined by high precision 14CO2 measurements to better than ±10% in winter and about ±30% in summer. • At remote sites, the mean FFCO2 signal is small (1-5 ppm) and can be determined by 14CO2 measurements only to about 30%. Higher temporal resolution of 14CO2 measurements is required here to achieve better precision.
Conclusions (II): CO is a potentially applicable surrogate tracer for FFCO2, however, • Emissions inventories of CO (and FFCO2) are yet not accurate enough to apply it quantitatively, • CO has sources other than from fossil fuel burning (soils !!) which also need to be known accurately • The catchment area and relative mix of emissions needs to be known accurately, this requires modelling See REMO results from Karstens et al., Poster FF-134
Comparison of measured and REMO-modelled CO and FFCO2 mixing ratios
Comparison of measured and REMO-modelled CO/FFCO2 ratios Mean ratios [ppb/ppm]: Observations: 13.5±0.6 REMO & EDGAR: 12.7±0.1 REMO & IER: 11.0±0.2 See also Poster by Ute Karstens et al. No. FF-134
CO/CO2 fossil fuel emission ratios 2000 EDGAR V3.2 FT 2000 (Olivier et al., 2005) IER mean 2000 (Scholz et al., IER 2005) in mmol / mol