Permanent Urban Column Network for Carbon Emission Monitoring in Munich

Abstract:

Urban areas contribute to more than 70% of global fossil fuel CO₂ emissions and therefore represent a hotspot of the greenhouse gas (GHG) emissions. For an effective emission reduction, accurate and continuous monitoring systems for urban emissions are a prerequisite.

We present the Munich urban column sensor network, consisting of 5 automated solar-tracking spectrometer systems (EM27/SUN), that has been permanently measuring GHGs based on the principle of differential column measurements (DCM), starting in summer 2019. The measured differences between upwind and downwind columns are relatively insensitive to the vertical redistribution of tracer masses and surface fluxes upwind of the city, and therefore, well-suited to quantify GHG emissions. We developed a fully automated enclosure system for measuring CO₂, CH₄ and CO column-averaged concentrations.

Furthermore, we demonstrate the capabilities of such a sensor network by presenting the emission quantification of Munich, when combining our measurements with an inverse modeling framework that we have developed. Thanks to the automation, we were also able to continue the measurements during the COVID-19 lockdown in spring 2020. By correlating the CO₂ column concentration gradients to the traffic volume, we demonstrate that our network is well capable to detect variations in urban emissions.