Looking at the sun to trace greenhouse gases
In the same year as the international community negotiates the next global climate protocol in Paris (COP21), the Karlsruhe Institute of Technology (KIT) and IPSL laboratories LSCE , LERMA and LISA conducted a joint measurement campaign COCCON-Paris (COllaborative Carbon Column Observing Network) to measure CO2 and CH4 concentrations in the Paris megacity area between mid April and May 2015. Six transportable ground-based FTIR (Fourier Transform InfraRed spectroscopy) instruments, jointly developed by Bruker and KIT, were deployed to measure total columns, i.e. vertically integrated concentrations, CO2&CH4 in and around greater Paris. We make use of the fact that, as the sun light passes through the atmosphere the gases in it absorb specific (well-known) wavelengths. The absorption strength can then be related to the concentrations of e.g. CO2 in the atmosphere.
The COCCON Paris campaign did take place in the Parisian area from April 27 through May 16, 2015. The instruments were set up in the city center (Jussieu) and at four stations at almost equal distance from the center, including Gif-sur-Yvette (LSCE campus), Saulx-les-Chartreux, Piscop, Mitry-Mory (see map for measurement stations). After a first successful campaign in Berlin/Germany last year of the KIT group, this is the first such measurement campaign in a European megacity (metropolitan area with population in excess of 10 million inhabitants), which aims at the measurement of GHGs columns. Now that all data is processed, LSCE is working on the atmospheric modelling which will then help to estimate the anthropogenic emissions of Paris from the observed greenhouse gas concentrations. (Adapted from the official IPSL website release)