MUCCnet: Munich Urban Carbon Column network

Abstract

Abstract. In order to mitigate climate change, it is crucial to understand urban greenhouse gas (GHG) emissions precisely, as more than two-thirds of the anthropogenic GHG emissions worldwide originate from cities. Nowadays, urban emission estimates are mainly based on bottom-up calculation approaches with high uncertainties. A reliable and long-term top-down measurement approach could reduce the uncertainty of these emission inventories significantly. We present the Munich Urban Carbon Column network (MUCCnet), the world's first urban sensor network, which has been permanently measuring GHGs, based on the principle of differential column measurements (DCMs), since summer 2019. These column measurements and column concentration differences are relatively insensitive to vertical redistribution of tracer masses and surface fluxes upwind of the city, making them a favorable input for an inversion framework and, therefore, a well-suited candidate for the quantification of GHG emissions. However, setting up such a stationary sensor network requires an automated measurement principle. We developed our own fully automated enclosure systems for measuring column-averaged CO2, CH4 and CO concentrations with a solar-tracking Fourier transform spectrometer (EM27/SUN) in a fully automated and long-term manner. This also includes software that starts and stops the measurements autonomously and can be used independently from the enclosure system. Furthermore, we demonstrate the novel applications of such a sensor network by presenting the measurement results of our five sensor systems that are deployed in and around Munich. These results include the seasonal cycle of CO2 since 2015, as well as concentration gradients between sites upwind and downwind of the city. Thanks to the automation, we were also able to continue taking measurements during the COVID-19 lockdown in spring 2020. By correlating the CO2 column concentration gradients to the traffic amount, we demonstrate that our network is capable of detecting variations in urban emissions. The measurements from our unique sensor network will be combined with an inverse modeling framework that we are currently developing in order to monitor urban GHG emissions over years, identify unknown emission sources and assess how effective the current mitigation strategies are. In summary, our achievements in automating column measurements of GHGs will allow researchers all over the world to establish this approach for long-term greenhouse gas monitoring in urban areas.

Quantification of CH<sub>4</sub> emissions from waste disposal sites near the city of Madrid using ground- and space-based observations of COCCON, TROPOMI and IASI

“…Several successful field campaigns and long-term deployments have demonstrated that the Bruker EM27/SUN FTIR spectrometer is an excellent instrument with good quality, robustness and reliability and its performance offers the potential to support TCCON (Frey et al, 2015 andKlappenbach et al, 2015;Chen et al, 2016;Butz et al, 2017;Sha et al, 2019;Jacobs et al, 2020;Tu et al, 2020a and2020b;Dietrich et al, 2021). The Bruker EM27/SUN spectrometers have become commercially available from April 2014 onwards and currently about 70 spectrometers are operated by different working groups in Germany, France, Spain, Finland, Romania, USA, Canada, UK, India, Korea, Botswana, Japan, China, Mexico, Brazil, Australia and New Zealand.…”

“…Due to the ruggedness of the portable devices used and simple operability, COCCON is well suited for implementing arrays of spectrometers for the quantification of local GHG sources (Hase et al, 2015;Luther et al, 2019;Vogel et al, 2019;Dietrich et al, 2021).…”

An Interpolation Method to Reduce the Computational Time in the Stochastic Lagrangian Particle Dispersion Modeling of Spatially Dense XCO2 Retrievals

“…Observational networks such as the Utah Urban Carbon Dioxide Network (UUCON) and mobile rail‐based (TRAX) measurements in Salt Lake City, UT (Bares et al., 2019; Mitchell, Crosman, et al., 2018), the Indianapolis Flux Experiment (INFLUX) in Indianapolis, IN (Richardson et al., 2017), the Berkeley Environmental Air Quality & CO 2 Network (BEACON) in San Francisco, CA (Shusterman et al., 2016), the Los Angeles Megacity Carbon Project in Los Angeles, CA (Verhulst et al., 2017), and the Munich Urban Carbon Column Network (MUCCnet) in Munich, Germany (Dietrich et al., 2021) all provide insights into the spatiotemporal dynamics of these urban emissions. It is often the case that urban emissions produce atmospheric CO 2 concentrations that are measurably higher than regional baseline values (Jacobson, 2010; Wang & Ostoja‐Starzewski, 2004).…”

The CO<sub>2</sub> integral emission by the megacity of St. Petersburg as quantified from ground-based FTIR measurements combined with dispersion modelling

“…The core instruments of the campaign were two portable FTIR (Fourier Transform InfraRed) spectrometers (Bruker EM27/SUN) which were used for ground-based remote sensing measurements of the total column amount of CO 2 , CH 4 and CO at upwind and downwind locations on opposite sides of the city. The applicability and efficiency of this measurement scenario and EM27/SUN spectrometers have been shown by Hase et al (2015), Chen et al (2016) and Dietrich et al (2021). The description of the EMME experiment has been given in full detail in the paper by Makarova et al (2021).…”