ICOS Science Conference 2020: Day 2, Plenary

1. Can we see a covid-19 impact in
atmospheric GHGs? A diagnostic
assessment using STILT
Christoph Gerbig1, Michal Galkowski1, Saqr Munassar1,
Santiago Botia B.1, Thomas Koch2, Dagmar Kubistin2, Michel
Ramonet3, and Ute Karstens4
1. Max Planck Institute for Biogeochemistry, Jena, Germany
2. Deutscher Wetterdienst, Germany
3. Laboratoire des Sciences du Climat et de l’Environnement, Gif sur Yvette, France
4. ICOS Carbon Portal, Lund University, Sweden
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ICOS Science Conference 2020

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Background
Emission drop during Covid restrictions:
• Great chance to test capability of current atmospheric network
for detection of related signatures
Le Quere et al.,
Nature Climate Change 2020
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Background
Emission drop during Covid restrictions:
• Great chance to test capability of current atmospheric network
for detection of related signatures
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Design of ICOS atmospheric network:
• Targeting biosphere-atmosphere fluxes
• Sites away from strong emission
hotspots
• Reduced impact from (uncertain)
emissions at fine spatiotemporal scales
Background
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Aproach
• Simulate CO2, CH4 and CO for 2014-2020 at multiple
stations across Europe assuming current emission
trends
• Use the difference between observed and simulated
mole fractions Cobs-mod
• Compare Cobs-mod for 2014-2019 to those of the current
year (2020)
• Assess the significance of any covid-19 related GHG
signals
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STILT Simulations
• EDGAR-BP: sector/fueltype specific, annually updated using BP statistical report 2019, similar to COFFEE
dataset aproach (Steinbach et al., 2011)
• Known bias in VPRM biospheric fluxes corrected using
CarboScope regional inversions (2016-2018 posterior – prior fluxes added)
• CAMS FC: high resolution forecast fields (provided by Anna Agusti-Panareda)
• Model domain covering Europe
• Transport model resolution: 10 km, hourly
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Emissions Natural
fluxes
Biomass
burning
Lateral
boundary
Lateral boundary 2
(bias correction)
CO2 EDGAR-BP VPRM GFAS CarboScope CAMS FC
CO EDGAR-BP GFAS CAMS FC
CH4 EDGAR-BP GFAS CAMS FC CAMS SRON

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Observations
ICOS L2 release 2019
ICOS L1 release 2020
2018 Drought dataset
A big THANK YOU to all data providers!
Only using daytime hours (12-17 LT)
Only using sites with few gaps in all species (CO2, CO, CH4) during March-June
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Observed and simulated CO2

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Observed and simulated CO2

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Observed and simulated CO2

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Observed and simulated CO2

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Observed and simulated CO

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Observed and simulated CO

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Observed and simulated CO

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Observed and simulated CO (CAMS)

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Observed and simulated CH4

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Observed and simulated CH4

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Observed and simulated CH4

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Observed and simulated CH4

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“regional” signals 20
Subtracting the tracer contribution from the lateral boundary:
Creg = C – CLBC
Creg corresponds to the contributions of within-domain fluxes

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Observed and simulated “regional” CO2

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Observed and simulated “regional” CO

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Observed and simulated “regional” CH4

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Observed “regional” CO2

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Observed “regional” CO

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Observed “regional” CH4

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Observed and simulated “regional” CO2 27
Averaging over sites (GAT, HPB, HTM, IPR, NOR, PAL, SMR, and SVB)

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Observed and simulated “regional” CO 28
Averaging over sites (GAT, HPB, HTM, IPR, NOR, PAL, SMR, and SVB)

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Scaling CO fluxes to match obs. during 2018-2019
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adjusting
background and
emissions for each
site using linear fit
2018-2019
(Mar-Jun only)

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After adjusting
background and
emissions for each
site using linear fit
2018-2019
(Mar-Jun only)
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Observed and simulated “regional” CO
Averaging over sites (GAT, HPB, HTM, IPR, NOR, PAL, SMR, and SVB)

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Observed and simulated “regional” CH4 31
Averaging over sites (GAT, HPB, HTM, IPR, NOR, PAL, SMR, and SVB)

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Observation – simulation differences 32
Expected pattern, with a near perfect model without reduction in
emissions:
Previous years
2020, with reduced CO2
after mid March (week 11)

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Mar 15
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Observed minus simulated CO2

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Mar 15
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Observed minus simulated CO

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Observed minus simulated and fitted CO
Mar 15
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Mar 15
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Observed minus simulated CH4

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Observed minus simulated CO2 37
Averaging over sites (GAT, HPB, HTM, IPR, NOR, PAL, SMR, and SVB)
Expected pattern, with
a near perfect model
without reduction in
emissions:

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Observed minus simulated CO2
Averaging over sites (GAT, HPB, HTM, IPR, NOR, PAL, SMR, and SVB)
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Expected signal from
reduced emissions
(~20% in CO2) using
sectorial reductions
(carbonmonitor.org
numbers)
Expected

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Concluding remarks
• Using regional simulations with STILT, no significant
covid-19 related change in the difference between
observations and simulations could be detected
• Improved models are needed to better represent GHG
observations
• Expected signals are small at ICOS sites (sites away
from emission hotspots)
• Extension of the network to include more polluted
sites is recommended
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