Potential of 14C-based versus ∆CO-based ∆ffCO2 observations to estimate urban fossil fuel CO2(ffCO2) emissions
<p><strong class="journal-contentHeaderColor">Abstract.</strong> Atmospheric transport inversions are a powerful tool for independently estimating surface CO<sub>2</sub> fluxes from atmospheric CO<sub>2</sub> concentration measurements. However, ad...
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| Hauptverfasser: | , , , , , |
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| Dokumenttyp: | Article (Journal) Kapitel/Artikel |
| Sprache: | Englisch |
| Veröffentlicht: |
3 July 2023
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| In: |
EGUsphere
Year: 2023, Pages: 1-30 |
| DOI: | 10.5194/egusphere-2023-1239 |
| Online-Zugang: | Resolving-System, kostenfrei, Volltext: https://doi.org/10.5194/egusphere-2023-1239 Verlag, kostenfrei, Volltext: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-1239/ 
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| Verfasserangaben: | Fabian Manuel Maier, Christian Rödenbeck, Ingeborg Levin, Christoph Gerbig, Maksym Gachkivskyi, and Samuel Hammer |
| Zusammenfassung: | <p><strong class="journal-contentHeaderColor">Abstract.</strong> Atmospheric transport inversions are a powerful tool for independently estimating surface CO<sub>2</sub> fluxes from atmospheric CO<sub>2</sub> concentration measurements. However, additional tracers are needed to separate the fossil fuel CO<sub>2</sub> (ffCO<sub>2</sub>) emissions from natural CO<sub>2</sub> fluxes. In this study we focus on radiocarbon (<sup>14</sup>C), the most direct tracer for ffCO<sub>2</sub>, and the continuously measured surrogate tracer carbon monoxide (CO), which is co-emitted with ffCO<sub>2</sub> during incomplete combustion. In the companion paper by Maier et al. (2023a) we determined for the urban Heidelberg observation site in Southwestern Germany discrete <sup>14</sup>C-based and continuous ∆CO-based estimates of the ffCO<sub>2</sub> excess concentration (∆ffCO<sub>2</sub>) compared to a clean-air reference. Here, we use the CarboScope inversion framework adapted for the urban domain around Heidelberg to assess the potential of both types of ∆ffCO<sub>2</sub> observations to investigate ffCO<sub>2</sub> emissions and their seasonal cycle. We find that discrete <sup>14</sup>C-based ∆ffCO<sub>2</sub> observations from almost 100 afternoon flask samples collected in the two years 2019 and 2020 are not well suited for estimating robust ffCO<sub>2</sub> emissions in the main footprint of this urban area with a very heterogeneous distribution of sources including several point sources. The benefit of the continuous ∆CO-based ∆ffCO<sub>2</sub> estimates is that they can be averaged to reduce the impact of individual hours with an inadequate model performance. We show that the weekly averaged ∆CO-based ∆ffCO<sub>2</sub> observations allow for a robust reconstruction of the seasonal cycle of the area source ffCO<sub>2</sub> emissions from temporally flat a-priori emissions. In particular, the distinct COVID-19 signal with a steep drop in emissions in spring 2020 is clearly present in these data-driven a-posteriori results. Moreover, our top-down results show a shift in the seasonality of the area source ffCO<sub>2</sub> emissions around Heidelberg in 2019 compared to the bottom-up estimates from TNO. This highlights the huge potential of ∆CO-based ∆ffCO<sub>2</sub> to verify bottom-up ffCO<sub>2</sub> emissions at urban stations if the ∆CO / ∆ffCO<sub>2</sub> ratios can be determined without biases.</p> |
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| Beschreibung: | Im Titel ist die Zahl 14 hochgestellt, 2 jeweils tiefgestellt Gesehen am 05.02.2024 |
| Beschreibung: | Online Resource |
| DOI: | 10.5194/egusphere-2023-1239 |