combined 14 co 2 and co observations: a key to high-resolution fossil fuel co 2 records ? ! ingeborg...
DESCRIPTION
Schauinsland station of the Umweltbundesamt in the Black Forst 1205 m a.s.l.TRANSCRIPT
Combined 14CO2 and CO Observations:
A key to high-resolution fossil fuel CO2 records ? !
Ingeborg Levin1 and Ute Karstens2
1Institut für Umweltphysik Universität Heidelberg
2Max-Planck-Institut für Biogeochemie, Jena
Outline• Importance of fossil fuel CO2 emissions for the CO2
mixing ratio over Europe
• Determination of atmospheric fossil fuel CO2 by 14CO2 observations
• Correlation fossil fuel CO2 with CO
• Assessment of a purely observation-based method to derive hourly atmospheric fossil fuel CO2
Schauinsland station of the Umweltbundesamt in the Black Forst 1205 m
a.s.l.
Comparison of REMO-simulated CO2 mixing ratios at Schauinsland with observations
February 2002
July 2002
How can we measure fossil fuel CO2 in the atmosphere to validate these
model results ?
Radiocarbon 14C (14C, radioactive lifetime = 8300 years)
Natural 14C production by reactions of neutrons from cosmic radiation with atmospheric Nitrogen natural atmospheric background level
Artificial 14C production via atmospheric nuclear weapon tests in the 1950s and 1960s
„Negative 14C source“ via burning of fossil fuels and cement production which are free of 14C
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
0
50
100
150
200
Jungfraujoch (cont. reference) Schauinsland monthly means Heidelberg monthly means
14
C [‰
]
0
5
10Schauinsland
1985 1990 1995 2000 20050
20
40 total CO
2 offset
fossil fuel offset
Heidelberg
foss
il fu
el C
O2 [p
pm]
The temporal resolution of 14C-derived fossil fuel CO2 is not sufficient to validate high-resolution
model simulations
Heidelberg sampling site in the populated Rhine valley
How well do CO mixing ratios correlate with fossil fuel CO2 ?
Use a combination of integrated 14CO2 and hourly CO measurements :
weeklymeashourly
basedCweekly2meas
hourlyhourly2CO
)foss(COCO)foss(CO
14
Test this approach in the REMO model world :
weeklymodhourly
weeklymodhourly2
modhourly
calculatedrehourly2
CO
)foss(COCO)foss(CO
Assess the difference between original and re-calculated hourly CO2(foss) -> RMS deviation
Test with REMO model run for Heidelberg
Annual mean CO2 foss [ppm] RMS error [ppm] RMS error [%]:
IER: 18.0 3.2 18EDGAR: 16.1 2.3 14
REMO-simulated fossil fuel CO2 in Europe and RMS difference to CO-based approach (Feb.
2002)
→ In most of Europe the CO-based method has RMS errors below 30%
Fossil fuel CO2 RMS error
Can we validate our suggested method to derive fossil fuel CO2 from integrated
14CO2 and hourly CO observations in the real world ?
23.04.2002 24.04.2002380
400
420
440
460 CO
2(foss) 14C-based
CO2(foss) CO-based
CO2 flasks
CO2 continuous
CO
2 [ppm
]
15.08.2002 16.08.2002
380
400
420
440
460
480 CO2(foss) 14C-based CO
2(foss) CO-based
CO2 flasks
CO2 continuous
CO
2 [ppm
]
Event samples collected in Heidelberg [data from Gamnitzer et al., 2006]
RMS deviation: 34 % RMS deviation: 32 %
RMS deviation: 23 % RMS deviation: 20 % 25.02.2003 26.02.2003 27.02.2003
400
450
500
550 CO2(foss) 14C-based
CO2(foss) CO-based
CO2 flasks CO
2 continuous
CO
2 [ppm
]
30.10.2002 31.10.2002380400420440460480500
CO2(foss) 14C-based
CO2(foss) CO-based
CO2 flasks
CO2 continuous
CO
2 [ppm
]
Summary :• Fossil fuel CO2 emissions in Europe contribute between 30% and 50% to
the atmospheric short-term (diurnal) CO2 signal and also to the monthly mean continental signal both, at urban and remote (mountain) sites
• CO is a good surrogate tracer for FFCO2 if well calibrated with 14CO2 observations, and can thus provide FFCO2 at high temporal resolution
• But: Calibration needs to be an ongoing exercise
• Combined weekly or two-weekly integrated 14CO2 and hourly CO observations allow to determine hourly fossil fuel CO in Europe with uncertainties between 15 and 40% (depending on the relative importance of the fossil fuel CO2 component)
• Our proposed method is purely observation-based and until now much more accurate and precise than any model-simulated approach [see Poster No. 179 by Karstens et al. ]
Suggestion for CarboEurope stations :
Establish high-precision integrated 14CO2 measurements at all stations where continuous CO measurements exist to “measure” hourly fossil fuel CO2 mixing ratios.
Thank you !
Test with REMO model run for Lutjewad
Annual mean CO2 foss [ppm] RMS error [ppm] RMS error [%]:
IER: 7.3 2.1 29EDGAR: 6.0 1.5 24
Test with REMO model run for Schauinsland
Annual mean CO2 foss [ppm] RMS error [ppm] RMS error [%]:
IER: 2.3 0.9 39EDGAR: 2.1 0.7 35
Continuous CO2 and CO mixing ratios in Heidelberg
01.02.2002 04.02.2002 07.02.2002 10.02.2002
250
500
750
1000
1250
01.02.2002 04.02.2002 07.02.2002 10.02.2002
380
400
420
440
460 CO
2 continuous
CO
2 [ppm
] CO continuous
CO
[ppb
]
11.07.2002 14.07.2002 17.07.2002 20.07.2002
250
500
750
1000
1250
11.07.2002 14.07.2002 17.07.2002 20.07.2002
380
400
420
440
460 CO2 continuous
CO
2 [ppm
] CO continuous
CO
[ppb
]
February2002
July2002
January 2002 CO2 Fluxes
Fossil fuel CO2 (extrap.)(Scholz et al., IER 2005)
Biome-BGC NEE (Churkina et al., 2003)
in 10-9 kg C m-2 s-1
IER: Inst. of Energy Economics and the Rational Use of Energy, Univ. Stuttgart, Germany
Calculation of the fossil fuel CO2 component from 14C observations
-120
-100
-80
-60
-40
-20
00 10 20 30 40
cbackground + cbio fossil CO2 offset [ppm]
14C
dep
letio
n [‰
]
1000CCCcc
BG14
meas14
BG14
measfossil