2025-12-09 スイス連邦材料試験研究所(EMPA)
“No diet can be successful without a scale,” summarizes Lukas Emmenegger, Head of Empa’s Laboratory for Air Pollutants / Environmental Technology the ICOS cities measurements. Image: Pekka Pelkonen / ICOS RI
＜関連情報＞
- https://www.empa.ch/web/s604/icos-cities-co2-emissionen-von-staedten-ermitteln
- https://acp.copernicus.org/articles/25/14279/2025/
- https://egusphere.copernicus.org/preprints/2025/egusphere-2025-3668/
- https://acp.copernicus.org/articles/25/2781/2025/
スイス、チューリッヒの高層ビルにおける多種渦共分散法を用いた温室効果ガスおよび汚染物質排出量の部門別帰属 Sectoral attribution of greenhouse gas and pollutant emissions using multi-species eddy covariance on a tall tower in Zurich, Switzerland
Rainer Hilland, Josh Hashemi, Stavros Stagakis, Dominik Brunner, Lionel Constantin, Natascha Kljun, Ann-Kristin Kunz, Betty Molinier, Samuel Hammer, Lukas Emmenegger, and Andreas Christen
Atmospheric Chemistry and Physics Published:30 Oct 2025
DOI:https://doi.org/10.5194/acp-25-14279-2025
Abstract
Eddy covariance measurement of species that are co-emitted with carbon dioxide (CO2), such as carbon monoxide (CO) and nitrogen oxides NO and NO2 (NOx), provides an opportunity to attribute a net flux to individual source or sink categories. We present eight months of continuous simultaneous measurements of fluxes (F) of CO2, CO, NOx, methane (CH4), and nitrous oxide (N2O) from a tall tower (112 m a.g.l.) in Zurich, Switzerland. Median daily fluxes of Fco2 were 1.47 times larger in the winter (November–March) as opposed to summer (August–October) months (10.9 vs. 7.4 µmol m−2 s−1); 1.08 times greater for FCO (30 vs. 28 nmol m−2 s−1); 1.08 times greater for FNOX (14 vs. 13 nmol m−2 s−1); 1.01 times greater for FCH4 (13.5 vs. 13.3 nmol m−2 s−1); and not statistically significantly different for FN2O. Flux ratios of FCO/Fco2 and FNOX/Fco2 are well characterised by inventory emission ratios of stationary combustion and road transport in cold months. In warm months both Fco/Fco2 and FNO/FCO2 systematically exceed expected inventory ratios during the day, while no statistically significant seasonal difference is observed in FNOX/FCO , indicating biospheric photosynthetic activity. A linear mixing model is proposed and applied to attribute half-hourly Fco2, FCO, and FNO to stationary combustion and road transport emission categories as well as determine the biospheric Fco2. Flux attribution is reasonable at certain times and from certain wind directions, but over-attributes CO and NOx fluxes to road traffic and CO2 fluxes to stationary combustion, and overestimates photosynthetic CO2 uptake.
ICON-ART CTDAS逆モデリングフレームワークを用いたチューリッヒとパリの都市におけるCO2フラックスの推定 Estimation of CO2 fluxes in the cities of Zurich and Paris using the ICON-ART CTDAS inverse modelling framework
Nikolai Ponomarev, Michael Steiner, Erik Koene, Pascal Rubli, Stuart Grange, Lionel Constantin, Michel Ramonet, Leslie David, Lukas Emmenegger, and Dominik Brunner
The EGU interactive community platform Published:15 Sep 2025
DOI:https://doi.org/10.5194/egusphere-2025-3668
Abstract.
Observation-based estimation of urban CO2 emissions can help cities track their pathway to net zero emissions, a goal many cities worldwide have adopted. While mesoscale atmospheric transport models are an effective component in inversion systems estimating country-level emissions, their use in urban-scale inversions presents a significant challenge. Here, we present one-year flux inversion results with the mesoscale ICON-ART atmospheric transport model for two cities with contrasting size and topographic complexity: Zurich and Paris. Inversions were performed with an ensemble square root filter, assimilating observations from a dense rooftop CO2 sensor network in Zurich and from a tall tower network in Paris. The inversion framework optimized gridded anthropogenic and biospheric fluxes, along with background mole fractions from eight inflow regions. Prior anthropogenic emissions were based on detailed inventories provided by local authorities. In Zurich, the inversion resulted in a posterior annual anthropogenic emission of 1012.3 ± 38.8 kt yr-1 representing approximately a 30 % reduction compared to the prior, with the most significant decreases during winter periods of elevated ambient temperatures. In contrast, the posterior fluxes in Paris remained close to the prior, with an annual emission of 3580.0 ± 101.9 kt yr-1, 7 % higher than the prior. This comparison highlights the influence of city-specific factors—such as topography, city size, and observational network—on the inversion system performance. Furthermore, our findings demonstrate the potential of mesoscale models to refine urban emission estimates, offering valuable insights for policymakers and researchers working to improve emission inventories and advance urban climate strategies.
ZiCOS-M CO2センサーネットワーク：チューリッヒ全域の測定性能とCO2変動 The ZiCOS-M CO2 sensor network: measurement performance and CO2 variability across Zurich
Stuart K. Grange, Pascal Rubli, Andrea Fischer, Dominik Brunner, Christoph Hueglin, and Lukas Emmenegger
Atmospheric Chemistry and Physics Published:04 Mar 2025
DOI:https://doi.org/10.5194/acp-25-2781-2025
Abstract
As a component of the ICOS Cities project, a “mid-cost” NDIR (nondispersive infrared) CO2 sensor network was deployed across the city of Zurich (Switzerland), known as ZiCOS-M. The network was operational between July 2022 and July 2024 and consisted of 26 monitoring sites, 21 of which were located in or around the city of Zurich, with 5 sites outside the urban area. Daily calibrations using two reference gas cylinders and corrections of the sensors’ spectroscopic response to water vapour were performed to reach a high level of measurement accuracy. The hourly mean root mean squared error (RMSE) was 0.98 ppm (range of 0.46 and 1.5 ppm) and the mean bias ranged between −0.72 and 0.66 ppm when undergoing parallel measurements with a high-precision reference gas analyser for a period of 2 weeks or more. CO2 concentrations (technically, dry-air mole fractions) were highly variable with site means in Zurich ranging from 434 to 460 ppm, and Zurich’s mean urban CO2 dome was 15.4 ppm above the regional background. Some of the highest CO2 levels were found at two sites exposed to strong plant respiration in a very confined nocturnal boundary layer. High-CO2 episodes were detected outside Zurich’s urban area, demonstrating that processes acting on a variety of scales drove CO2 levels. The ZiCOS-M network offered significant insights at a cost an order of magnitude lower compared to reference instruments, and the observations generated by ZiCOS-M will be used in additional ICOS Cities activities to conduct CO2 emission inventory validation with inversion modelling systems.
