1. CO/FFCO 2 RATIOS DERIVED FROM RADIOCARBON OBSERVATIONS - THE ROLE OF BIOSPHERIC COMPONENT KAZIMIERZ ROZANSKI AGH University of Science and Technology Krakow, Poland Krakow, Poland CarboEurope-IP Annual Meeting Poznan, 13-17.11.2006

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

3. METHODOLOGY: BALANCE EQUATIONS: CO 2mix = CO 2bgd +  CO 2bio) +  CO 2fossil (1) CO 2mix (  14 CO 2mix +1000) = CO 2bgd (  14 CO 2bgd +1000) CO 2mix (  14 CO 2mix +1000) = CO 2bgd (  14 CO 2bgd +1000) +  CO 2bio (  14 CO 2bio +1000) +  CO 2bio (  14 CO 2bio +1000) +  CO 2fossil (  14 CO 2fossil +1000) (2) +  CO 2fossil (  14 CO 2fossil +1000) (2) FFCO 2 = CO 2mix [(  14 CO 2bgd -  14 CO 2mix )/(  14 CO 2bgd + 1000)] FFCO 2 = CO 2mix [(  14 CO 2bgd -  14 CO 2mix )/(  14 CO 2bgd + 1000)]ASSUMPTIONS: (1)  14 C fossil = -1000 (2)  14 C bio =  14 C bgd (3) Regional background: Jungfraujoch (  14 C bgd, CO bgd ) BALANCE EQUATIONS: CO 2mix = CO 2bgd +  CO 2bio) +  CO 2fossil (1) CO 2mix (  14 CO 2mix +1000) = CO 2bgd (  14 CO 2bgd +1000) CO 2mix (  14 CO 2mix +1000) = CO 2bgd (  14 CO 2bgd +1000) +  CO 2bio (  14 CO 2bio +1000) +  CO 2bio (  14 CO 2bio +1000) +  CO 2fossil (  14 CO 2fossil +1000) (2) +  CO 2fossil (  14 CO 2fossil +1000) (2) FFCO 2 = CO 2mix [(  14 CO 2bgd -  14 CO 2mix )/(  14 CO 2bgd + 1000)] FFCO 2 = CO 2mix [(  14 CO 2bgd -  14 CO 2mix )/(  14 CO 2bgd + 1000)]ASSUMPTIONS: (1)  14 C fossil = -1000 (2)  14 C bio =  14 C bgd (3) Regional background: Jungfraujoch (  14 C bgd, CO bgd ) I. DERIVING LOCAL FFCO 2 (  CO 2fossil )

4. II. LOCAL  CO:  CO = CO mix - CO bgd III. LOCAL  CO/FFCO 2 RATIOS

6. Monthly  CO/FFCO 2 ratios in Krakow: 1992 – 1996 and 2000 - 2007 77.0  5.3 (ppb/ppm) 29.9  1.6 (ppb/ppm)

7. filter molecular diaphragm sieve pump CO 2 flowmeter silica gel Radiocarbon content of soil CO 2 flux ? Is the assumption  14 C bio =  14 C bgd valid ? Monthly ”composite” samples

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

10. Grassland site (Krakow)

11. CAB SDBFDB F f (1) F out FrFr FofFof FosFos F f (2) F f (n) FfFf F cw F in F s (1) F s (2) F s (n) FsFs TERRESTRIAL BIOSPHERE RRB ATMOSPHERE MODEL: F out (t) = F fast (t) + F slow (t) + F r (t) 14 A out (t) =  1 (t)  14 A fast (t) +  2 (t)  14 A slow (t) +  3  14 A r (t)

12. MODEL RESULTS: MRT fast = 14 years MRT slow = 1500 years Forest: M slow /M fast = 40 Grassland: M slow /M fast = 22

13.  14 C bio   14 C mix NEW ASSUMPTION: FFCO 2 = CO 2bgd [(  14 CO 2bgd -  14 CO 2mix )/(  14 CO 2mix + 1000)]  14 C bio =  14 C bgd X

14. Differences between FFCO 2 estimates

15. No a priori assumption about  14 C bio : FFCO 2 = CO 2mix [(  14 CO 2bio -  14 CO 2mix )/(  14 CO 2bio + 1000)] + CO 2bgd [(  14 CO 2bgd -  14 CO 2bio )/(  14 CO 2bio + 1000)] + CO 2bgd [(  14 CO 2bgd -  14 CO 2bio )/(  14 CO 2bio + 1000)] For  14 CO 2bio =  14 CO 2bgd + 40

16. SUMMING UP:  R adiocarbon content of soil CO 2 flux introduce additional uncertainty in the estimates of FFCO 2 which is difficult to eliminate.  However, it turnes out that radiocarbon-based FFCO 2 estimates are relatively insensitive to actual radiocarbon content of the biospheric component. For the current levels of FFCO 2 this additional uncertainty is in the order of 0.1- 0.5 ppm.  The modified formula for calculating FFCO 2 (assumption:  14 C bio   14 C mix ) opens up attractive possibilities for monitoring FFCO 2 variations with relatively good precision, even without regular high-precision observations of CO 2 concentations at those sites.

17. FFCO 2 KRAKOW - 1986 - 2007