Aix-Marseille Carbon Pilot Study (AMC)

Project ID Card
Aix-Marseille Carbon Pilot Study (AMC)
Project Call 
Project Dates 
Sep 2016 - Dec 2019
Relevant OT-MED work packages  
Project leader 
Irène Xueref-Remy & Dominique Lefèvre
Participants or laboratories 

Atmosphere sub-project:

Brian Nathan (OT-Med post-doc)
Irène Xueref-Remy (IMBE-PYTHEAS)
Mélissa Milne (Master 2 student)
Jacques Piazzola (MIO)
Christophe Yohia (PYTHEAS/SIP)
Alexandre Armengaud (ATMOSUD)
Pierre-Eric Blanc (PYTHEAS/OHP)

Biosphere sub-project:

Jean-Philippe MEVY (IMBE)

Andrea Paya (Master 2 student)

Ocean sub-project:

Katixa Lajaunie (OT-Med post-doc)
Cathy Wimart-Rousseau (PhD student)
Dominique Lefèvre, Frédéric DIAZ, Christel PINAZO, Thibault Wagener (MIO)

Context & Objectives  

This project aims at developping the base for a long‐term Carbon Observatory that will rely on a network of in‐situ CO2 sensors, repeated 14CO2 measurements, Lidar observations of the urban boundary layer in the context of the urban heat island and specific meteorology of the coastal area, an operational atmospheric transport model, and on the study of carbonaceous aerosols and other greenhouse gases such as CH4. 

This project is the first pilot study of atmospheric modelling of Marseille region based on a CO2 atmospheric approach. It aims at developing a mesoscale model to simulate the transport of atmospheric CO2 and pollutants (assessed against existing anf future datasets and AIRPACA modelled outputs) through the following sub-objectives :

1‐ Assessng the representativeness of the new in‐situ CO2 stations of the PACA region.
2‐ Developing a mesoscale transport modeling framework of atmospheric CO2 (and pollutants) for the PACA region, useful both for societal actors such as AIRPACA and for our research community.
3‐ Exploring the intensity and variability of the urban plume emitted by the Marseille area in function of the day, of the time of the day and of synoptic conditions.
4‐ Defining the atmospheric CO2 gradients upwind and downwind of the Marseille city in a marine, peri‐urban and a rural station.
5‐ Assessing if the CO2 and O3 plume emitted from the Marseille city impacts the NEE flux on the peri‐urban and rural ecosystems at CLIMED and O3HP stations.
6‐ Developing a regional marine carbonate chemistry model on the coastal Mediterranean Sea area of PACA.
7‐ Assessing the link between the variability of atmospheric CO2, pH and alkalinity in the coastal area of Marseille, and assess if the CO2 urban plume impacts these parameters.
8‐ Setting-up an observation program to record carbonate chemistry in the Bay of Marseille.

Main Results 
  • A CO2 urban plume reaching 100 parts per million above background was quantified in Marseille and its coastal area. Its variability was assessed in function of meteorological conditions and emissions
  • An atmospheric CO2 mesoscale model (WRF-CHEM) was developed and revealed issues in the regional emissions inventory
  • Based on marine and atmospheric measurements, the Bay of Marseille was identified to behave as a sink of carbon on an annual mean with some seasonal variability
  • Tests were performed on 3 different continental vegetal species exposed to elevated CO2 and ozone, showed that photosynthesis was increased up to a factor of 2.5 under 100 ppm-elevated atmospheric CO2 concentrations and different sensitivities of each species to ozone atrophy.

Fig.1 Regional atmospheric CO2 timeseries showing elevated CO2 concentrations (“the urban plume”) at Marseille and Endoume stations
(Xueref-Remy, Milne et al, WMO/IG3IS conference, 2018)

Lajaunie-Salla, K., Diaz, F., Wimart-Rousseau, C., Wagener, T., Lefèvre, D., Yohia, C., ... & Pinazo, C. (2020). Implementation and assessment of a carbonate system model (Eco3M-CarbOxv1. 1) in a highly-dynamic Mediterranean coastal site (Bay of Marseille, France). Geoscientific Model Development Discussions, 1-35.
Wimart-Rousseau C., Lajaunie-Salla K., Marrec P., Wagener T., Raimbault P., Lagadec V., Lafont M., Garcia N., Diaz, F., Pinazo P., Yohia C., Garcia F., Xueref-Remy I., Blanc P.E, Armengaud A., Lefèvre D. (2020). Temporal variability of the carbonate system and air-sea CO2 exchanges in a Mediterranean human-impacted coastal site. Estuarine, Coastal and Shelf Science, 236, 106641.