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CO/FFCO 2 RATIOS DERIVED FROM RADIOCARBON OBSERVATIONS - THE ROLE OF BIOSPHERIC COMPONENT

CarboEurope-IP Annual Meeting Poznan, 13-17.11. 200 6. CO/FFCO 2 RATIOS DERIVED FROM RADIOCARBON OBSERVATIONS - THE ROLE OF BIOSPHERIC COMPONENT. KAZIMIERZ ROZANSKI AGH University of Science and Technology Krakow, Poland. WP2.6 Objectives:.

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CO/FFCO 2 RATIOS DERIVED FROM RADIOCARBON OBSERVATIONS - THE ROLE OF BIOSPHERIC COMPONENT

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  1. CarboEurope-IP Annual Meeting Poznan, 13-17.11.2006 CO/FFCO2 RATIOS DERIVED FROM RADIOCARBON OBSERVATIONS -THE ROLE OF BIOSPHERIC COMPONENT KAZIMIERZ ROZANSKI AGH University of Science and Technology Krakow, Poland

  2. WP2.6 Objectives: • Continue the existing 14CO2 observation network in Europe to derive the monthly mean fossil fuel CO2 component at polluted • and background sites • Ongoing calibration of CO as a proxy for fossil fuel CO2 at 4 sites in Eastern and Western Europe • (Heidelberg, Krakow, Trainou Tower and Lutjewad)

  3. METHODOLOGY: I. DERIVING LOCAL FFCO2(CO 2fossil) • BALANCE EQUATIONS: • CO2mix = CO2bgd + CO2bio)+ CO2fossil (1) • CO2mix(14CO2mix+1000) =CO2bgd(14CO2bgd+1000) • +CO2bio(14CO2bio+1000) • +CO2fossil(14CO2fossil+1000) (2) • FFCO2 = CO2mix[(14CO2bgd - 14CO2mix)/(14CO2bgd + 1000)] • ASSUMPTIONS: • 14Cfossil = -1000 • 14Cbio = 14Cbgd • (3) Regional background: Jungfraujoch (14Cbgd, CObgd)

  4. II. LOCAL CO: CO = COmix - CObgd III. LOCAL CO/FFCO2 RATIOS

  5. Monthly CO/FFCO2 ratios in Krakow: 1992 – 1996 and 2000 - 2007 77.05.3 (ppb/ppm) 29.91.6 (ppb/ppm)

  6. filter silica gel flowmeter CO2 diaphragm molecular pump sieve Radiocarbon content of soil CO2 flux ? Is the assumption14Cbio= 14Cbgd valid ? Monthly ”composite” samples

  7. Three sites with different soil characteristics: - mixed forest - agriculture field - grassland (not cultivated)

  8. Grassland site (Krakow)

  9. ATMOSPHERE TERRESTRIAL BIOSPHERE Fin Fout RRB Fos Fof Fs (1) Ff (1) Fr Fs (2) Ff (2) SDB FDB Fs (n) Ff (n) Fs Ff Fcw CAB MODEL: Fout(t) = Ffast(t) + Fslow(t) + Fr(t) 14Aout(t) = 1(t)14Afast(t) + 2(t)14Aslow(t) + 314Ar(t)

  10. MODEL RESULTS: MRTfast=14 years MRTslow = 1500 years Forest: Mslow/Mfast = 40 Grassland: Mslow/Mfast = 22

  11. X 14Cbio = 14Cbgd NEW ASSUMPTION: 14Cbio  14Cmix FFCO2 = CO2bgd[(14CO2bgd - 14CO2mix)/(14CO2mix + 1000)]

  12. Differences between FFCO2 estimates

  13. No a priori assumption about 14Cbio: FFCO2 = CO2mix[(14CO2bio - 14CO2mix)/(14CO2bio + 1000)] + CO2bgd[(14CO2bgd - 14CO2bio)/(14CO2bio + 1000)] For14CO2bio= 14CO2bgd + 40

  14. SUMMING UP: • Radiocarbon content of soil CO2 flux introduce additional uncertainty in the estimates of FFCO2 which is difficult to eliminate. • However, it turnes out that radiocarbon-based FFCO2estimates • are relatively insensitive to actual radiocarbon content • of the biospheric component. For the current levels of FFCO2 • this additional uncertainty is in the order of 0.1- 0.5 ppm. • The modified formula for calculating FFCO2 (assumption: 14Cbio  14Cmix) opens up attractive possibilities for monitoring FFCO2 variations with relatively good precision, even without regular high-precision observations of CO2 concentations at those sites.

  15. FFCO2 KRAKOW - 1986 - 2007

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