Researchers from Karlsruhe Institute of Technology (KIT, Karlsruhe, Germany) have for the first time used several mobile Fourier Transform Spectrometers for detecting the CO2 emitted by a large metropolitan region in solar absorption spectra. The campaign was performed in June and July 2014 around Berlin, Germany, using five EM27SUN spectrometers (this type of spectrometer has been developed in a collaboration between researchers at KIT and Bruker Optics GmbH, Ettlingen). The results have been published recently and are currently accessible in AMTD (Frey et al., 2015, Hase et al., 2015).
The advantage of this novel approach is to directly measure the column-averaged abundances that are insensitive to assumptions on vertical exchange as opposed to eg. high precision surface in-situ measurements. However, due to the long atmospheric lifetime of CO2 the expected column-averaged CO2 enhancements are small compared to the background abundance, therefore the precision, instrument-to-instrument consistency and stability requirements are very high. The results prove the first successful demonstration of this novel approach. The KIT researchers now plan to initiate the new spectrometer type for highly accurate and precise observations of CO2 and CH4 around the globe by joining with other international collaborations.
The emerging network is named COCCON (Collaborative Carbon Column Observing Network) and will complement the established TCCON network with stations in remote areas and through dedicated campaigns. It is foreseen to associate COCCON with the FTIR activities in NDACC’s Infrared Working Group.