Quantifying CO2 emissions from Paris megacity: a correlation analysis between atmospheric CO2 and co-emitted species to infer the relative role of the different emission sectors.

Abstract:

With about 12 millions of inhabitants, Paris is the third megacity of Europe. Due to anthropogenic activities based on fossil fuel consumption (mainly gas heating and traffic) and cement production, inventories relate that Paris region emits about 55 millions of tons of CO2. These estimates come from inventories that are based on benchmarked emission factors and activity proxies. They are not verified independently, highlighting the need for developing new tools of monitoring-reporting-verifying Paris CO2 emissions. Since emissions are diluted into the atmosphere, atmospheric measurements and inverse transport modeling constitute tools of choice to develop such new methods, that one would ideally design to be useful for a large number of urbanized areas. Especially, when fossil fuels are burned, the combustion process leads to the atmospheric emission of not only CO2 but also CO and several other species that are specific of each combustible. Furthermore, the ratio of each species to CO2 is characteristic of the emission source, allowing the possible identification of the relative role of the different emission sectors on the total plume of CO2 emitted into the atmosphere. In the framework of several projects (CO2-Megaparis, Multi-CO2, Primequal-Zapa), one year of CO2 and CO in-situ measurements were monitored in Paris region. For a few weeks several other species were collected such as NOx, carbon isotopes (d12C, d13C, D14C) and volatile organic compounds. In this work, we will present the analysis of CO/CO2 ratios over a year but also an overwiew of the main results obtained through the analysis of correlations between CO2, NOx, VOCs and carbon isotopes collected during intensive campaigns in Paris.