ICOS Science Conference, Session 2

1. Pollution events, heatwaves, COVID lockdowns: what do we see
in our recent atmospheric CO2, CH4, N2O observations in France?
M.Ramonet1, M.Lopez1, C.Caldow1, C. Yver Kwok1, A.Colomb2, S.Conil3, F.Gheusi4, Y.Té5, T.Warneke6, I.Xueref Remy7, M.Delmotte1,
V.Kazan1, T.Laemmel1, O.Laurent1, V.Legendre1, C.Philippon1, L. Rivier1, A. Resovsky1, J.Tarniewicz1, P.Wiszniowski1 and P.Ciais1
1. Université Paris-Saclay, CEA, CNRS, UVSQ, Laboratoire des Sciences du Climat et de l'Environnement (LSCE/IPSL), Gif-sur-Yvette, France
2. Université Clermont Auvergne, CNRS, Laboratoire de Météorologie Physique, UMR 6016, Clermont-Ferrand, France
3. DRD/OPE, Andra, Bure, France
4. Laboratoire d’Aérologie, UPS Université Toulouse 3, CNRS (UMR5560), Toulouse, France
5. LERMA, UMR8112, PSL, Paris, France
6. Universität Bremen, Institute of Environmental Physics, Bremen, Germany
7. Aix Marseille Univ, Avignon Université, CNRS, IRD, Institut Méditerranéen de Biodiversité et d'Ecologie marine et continentale (IMBE), Marseille, France
Contact: Michel.Ramonet@lsce.ipsl.fr

2. Surface
Tall tower
TCCON
EM27
Aircore
The collaborative greenhouse gas measurement network in France
Coordination
Partners
CO2 continuous measurements at the surface
Nodata
 A growing, but quite recent network, built on different projects

3.  Can we see a covid-19 impact in atmospheric GHGs? A diagnostic assessment using STILT Christoph Gerbig et al.
 Changes in Net Ecosystem Exchange over Europe During the 2018 Drought Based on Atmospheric Inversions Rona Thompson et al.
 Spring enhancement and summer reduction in carbon uptake during the 2018 drought in northwestern Europe Naomi Smith et al.
 Assessment of regional atmospheric transport model performance using ²²²Radon observations Ute Karstens et al.
Using ICOS flux data to estimate prior uncertainty and its impact on simulated variability of atmospheric CO2 Anna Agusti-Panareda et al.
 In-situ continuous atmospheric greenhouse gases (CO₂, CH₄ and CO) measurements at the OHP
ICOS-Fr station tall tower in South France from July 2014 to March 2020 and related anthropogenic tracers Ludovic Lelandais et al.
 High quality trace gas measurements in the Marine Boundary Layer on Ships of Opportunity (SOOPs) Gregor Rehder et al.
 Towards greenhouse gas remote sensing evaluation using the AirCore atmospheric sampling system Bianca Baier et al.
 Methane vertical profile from ground-based FTIR measurements comparisons with AirCore measurements Minqiang Zhou et al.
during the Trainou campaign 2019

4. 2 mountain sites
2 coastal sites
1 peri-urban tall tower
4 rural towers
Ongoing: deployment of the ROC tall tower
in Brittany
French monitoring network :
background
surface sites

5. French monitoring network :
background & Paris region
surface sites
Paris area:
2 sites in Paris
5 sites in the suburbs (≈20 km)
Ongoing: deployment of 10 low(er) costs
instruments
Background
Urban
Local
emissions

6. August 2020
Gonnesse site:
influence of the landfill on CH4
Chris Caldow et al.
Ongoing analysis to relate the spikes to the landfill
emissions

7. Ramonet et al, Philosophical Transactions of the Royal Soc. B, 2020
Ramonet, M., P. Ciais, F. Apadula, A. Bastos, P. Bergamaschi, P. E. Blanc, D. Brunner, L. C. d. Torchiaro, F. Calzolari, H. Chen, L.
Chmura, A. Colomb, S. Conil, P. Cristofanelli, E. Cuevas, R. Curcoll, M. Delmotte, A. d. Sarra, G. Forster, A. Frumau, C. Gerbig, F.
Gheusi, S. Hammer, L. Haszpra, J. Hatakka, L. Hazan, M. Heliasz, S. Henne, A. Hensen, O. Hermansen, J. Holst, P. Keronen, K.
Kominkova, D. Kubistin, O. Laurent, T. Laurila, J. Lavric, I. Lehner, A. Leskinen, M. Leuenberger, I. Levin, M. Lindauer, M. Lopez, C.
L. Myhre, I. Mammarella, G. Manca, A. Manning, M. V. Marek, P. Marklund, D. Martin, F. Meinhardt, N. Mihalopoulos, M.
Molder, J. A. Morgui, J. Necki, S. O'Doherty, C. O'Dowd, M. Ottosson, C. Philippon, S. Piacentino, J. M. Pichon, C. Plass-Duelmer,
K.Rigel, L.Rivier, H. Scheeren, D. Sferlazzo, T. G. Spain, K. M. Stanley, M. Steinbacher, P. Trisolano, A. Vermeulen, G. Vítková, D.
Weyrauch, I. Xueref-Remy, K. Yala and C. Y. Kwok
The fingerprint of the summer 2018 drought in Europe on
ground-based atmospheric CO2 measurements.
https://doi.org/10.1098/rstb.2019.0513

8. M. Ramonet, and 80 co-authors
PTRS-B, 2020
Impact of the 2018 summer drought on atmospheric CO2 in Europe
Mean signal
+1.5 ppm
CO2 Anomaly in August 2018

9. March 2019 March 2020
+5°
-5°
Spring temperature anomaly Spring 2020 anomaly
NO2 tropospheric columns
2020: a very special year
Paris downtown20 km from Paris100 km from Paris
Trainou Saclay Paris-CDS
Lockdown

10. CO2 anomaly in August 2018 and 2020
CO2 seasonal cycles
in 2018 and 2020
Impact on a smaller area in 2020 compared to 2018,
but stronger signal in France

11. Paris region
NOx
CO
CO2
1st Jan 31 AugLockdown
Atmospheric concentrations in Paris downtown

12. 1
2
Saclay
Concentration gradients Paris - Saclay
NOx : -80%
CO : -84%
CO2 : -65%2020
Climato
 mean decrease of the gradient
during the lockdown ±15%
Site 1 - Saclay Site 2 - Saclay

13. NOx CO CO2
Urban sites
Rural site
Strong reduction of
the rush hours peaks
of NOx and CO
(reduction of the
traffic by about 80%
according to City
authorities)
Simultaneously with the start of
confinement, a reversal of the wind
direction is observed. Meteorological
situation remained atypical for several
days during the confinement.
Difference of
concentrations
between Saclay
and the 2 sites
in Paris
Lockdown period
Climatology
Lockdown
South-west winds North-east winds
March 2020

14.  French collaborative monitoring network for greenhouse gases: 10 surface sites in background and rural sites, and 7 sites in
Paris area (where 10 lower-cost instruments are currently being deployed)
 Emerging measurements: three sites with EM27 and aircore measurements (see next slides)
 Investment proposal in collaboration with ACTRIS-France and IAGOS-France in order to strengthen collaborations between RIs
and with the national data center (AERIS)
 2020 a very special year :
oDrought 2020 appears to be more important than 2018 in France according to the CO2 anomalies in the seasonal cycles
oThe impact of the confinement period hardly seen in the background sites, but has a significant impact on the CO2
gradients in Paris area.
oAtmospheric inversion of the signal in Paris is ongoing (Lian et al.)
oChallenging issue to discriminate between very special anthropogenic emissions, biospheric fluxes and atmospheric
transport. Use of additional observations (meteorological parameters, boundary layer heights, 14CO2, eddy fluxes, air
quality, activity statistics) will be essential. Many dataset are available in the case of Paris but their (ongoing) integration
and analysis need some time. Strong interest of the City of Paris for the quantification of impact of the shutdown on GES
emissions.

15. Total column measurements
 Two TCCON sites located in France (Trainou/Orléans, Jussieu/Paris)
 Three sites equipped with EM27/Sun (Saclay, Aire-Adour, Reims)
Setting up a regular side-by-side
intercomparison program
Development of a waterproof
casing for continuous operations
First campaigns performed in
Trainou and Paris area
(surface & total columns)
ICOS
towers
Total
columns
CO2
CH4
CO

16. AIRCORE measurement program
TRAINOU 2016-2019
CO2
CH4
CO
N2O
 Objective to perform monthly launches at 3 sites (Saclay, Aire-Adour, Reims)
 About 100 launches performed since Sep. 2016
 Organisation of one intensive campaign per year combining aircore, aircraft, total columns
 See Baier et al., Zhou et al., Chen et al. presentations