Radiocarbon Measurement Network in Europe - DWD
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COSMO-GHG Simulations of 14C to Support the Design of a
Radiocarbon Measurement Network in Europe
Michael Jähn1,a and Dominik Brunner1
(1) Swiss Federal Laboratories for Materials Science and Technology (Empa), Dübendorf, Switzerland
(a) Now at: ETH Zürich, Center for Climate Systems Modeling (C2SM), Switzerland
ICCARUS 2021, Online Poster Presentation
10 March 2021
ICCARUS 2021, 10 March 2021 | michael.jaehn@env.ethz.ch
Radiocarbon (14C) in the Atmosphere
Problem: CO2 signals from fossil fuel
combustion are difficult to distinguish from
biospheric CO2 signals
Can additional tracers like 14CO2 and CO
help discriminate between anthropogenic and
biospheric CO2?
How should a ground-based measurement
network of these tracers be designed?
Wang et al. (2016)
ICCARUS 2021, 10 March 2021 | michael.jaehn@env.ethz.ch 2
COSMO-GHG Modeling Setup and Tracers
COSMO-GPU with greenhouse gas (GHG) extension Origin Process Tracer Region Number
names split of tracers
European Domain, 5.5 km grid spacing Anthropogenic Fossil fuels CO2_FF Yes 6
Input data pre-processed on modeling domain (1 h CO_FF 6
Biofuels CO2_BF Yes 6
temporal resolution) C14_BF 6
Simulated trace compounds: CO2, 14CO2 and CO CO_BF 6
Nuclear power plants C14_NUC Yes 6
January and July 2015 simulated (hourly output data)
Biosphere GPP/NPP CO2_GPP Yes 6
Tagged tracers by region, source and background tracers C14_NPP 6
C14_NPN 6
Respiration CO2_RA Yes 6
C14_HR 6
Ocean Sources CO2_O_P No 1
(positive flux: "_P") CO2_O_N 1
CO_O_P 1
Sinks CO_O_N 1
(negative flux: "_N") C14_O_P 1
C14_O_N 1
IC/BC Background concentration CO2_BG No 1
from outside of domain C14_BG 1
CO_BG 1
SUM 75
No C14_FF tracer is needed since δ14CO2 = -1000 ‰ for fossil fuel processes and
[1]
the corresponding CO2-tracers can be used for the computation during post-processing.
ICCARUS 2021, 10 March 2021 | michael.jaehn@env.ethz.ch 3
Instantaneous Model Output of 14CO2 Tracers
Background Anthropogenic Ocean + Biosphere
ICCARUS 2021, 10 March 2021 | michael.jaehn@env.ethz.ch 4
Variations of Fossil Fuel CO2 and CO
Near-surface standard deviation ratios
Std-ratio CO2,fossil/14CO2,total
for most terrestrial areas close
to 100% in January 2015
Jan 2015
Distinctly lower values located
near nuclear power plants
More complex situation in July
due to biospheric activity
(above 90% in Central and
eastern Europe, significantally
less in other regions)
Std-ratio CO,fossil/CO,total high
Jul 2015
in densely populated and
industrial areas
Fossil fuel contribution to
variations in CO much lower
compared to 14CO2
ICCARUS 2021, 10 March 2021 | michael.jaehn@env.ethz.ch 5
Source Separation at Milan, Italy (Urban Station)
Jul
Jan
2015
2015
Emissions from fossil fuels dominate 14CO2 signal HR and biofuels add up to a non-negligible contribution to
14CO (even more pronounced for rural stations)
CO2 also dominated by fossil fuels, but not as much as 2
14CO Biospheric signals in CO2 significantly larger than fossil fuel
2
Biofuels = important source of CO emissions CO = attractive fossil fuel tracer in summer if background
concentration can be separated
ICCARUS 2021, 10 March 2021 | michael.jaehn@env.ethz.ch 6
Recommendations for the Surface Network
Fossil fuel signals much larger in winter compared to summer
more prominent contribution in 14CO2, CO2 and CO variability
Emission signal at certain station mostly dominated by the region it is located in
Long-range transport from neighboring regions plays an inferior role
Nuclear power plant emissions can have significant effect on radiocarbon measurements
(only in close proximity and during periods when the plume reaches the station)
Radiocarbon
Extremely valuable tracer of fossil fuel CO2 emissions
Winter: 90% - 100% 14CO2 variability by fossil fuel emissions
Summer: 70% - 80% 14CO2 variability by fossil fuel emissions
Carbon monoxide
Particularly valuable tracer of fossil fuel emissions during summer (reduced use of biofuels)
However not true during periods of biomass or agricultural waste burning
Large-scale variations in background CO to be separated from smaller-scale variations in fossil
fuel CO
High-frequency tracer to apply a time interpolation between (weekly) 14C measurements
ICCARUS 2021, 10 March 2021 | michael.jaehn@env.ethz.ch 7
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