The monitoring network of greenhouse gas (CO2, CH4) in the Paris' region
Résumé
There is a growing interest for the study of greenhouse gas emissions over urban areas. In this context, a network for measuring greenhouse gas concentrations was set up in Paris in 2015. Since then, seven stations located in and around Paris and equipped with cavity ring-down spectrometers (CRDS) have been monitoring gas concentrations of different species (CO 2 , CH 4 , CO) on a continuous basis. Procedures for maintenance, calibration, data processing have been adapted to ensure that the network is operational, providing good quality data in near-real time (NRT) and with high availability. The CO 2 and CH 4 concentrations show a growth rate of the baseline (linear trend of the averaged concentrations over the Paris region) concentrations (+2.34 ppm CO 2 /year and +11.1 ppb CH 4 /year) between 2015 and 2022 consistent with that observed at remote observatories such as Jungfraujoch (Switzerland). The amplitude of the CO 2 seasonal cycle is around 20 ppm (i.e. around 5%) while that of CH 4 is 40 ppb (i.e. around 2%). The concentration gradients calculated as the differences between up-and down-wind concentrations, can be used to infer the emissions for long lived species. We use the measurements from the 100m Saclay tower, outside of Paris, as a regional background during suitable wind direction conditions. The largest differences with these background measurements are observed in the two stations that are located within Paris (JUS and CDS), with urban offset up to ~50 ppm CO 2 and ~100 ppb CH 4 in winter and ~10 ppm CO 2 and ~50 ppb CH 4 in summer. In winter, the co-variability of CO and CO 2 hourly measurements (correlation coefficient r ~0.9 in all stations) indicates that the concentration variability is driven by anthropogenic emissions. Conversely, in summer, lower correlations between these
Domaines
Sciences de l'environnementOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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