Periodic Reporting for period 4 - COS-OCS (Carbonyl Sulphide: new ways of Observing the Climate System)
Berichtszeitraum: 2022-03-01 bis 2023-02-28
Zusammenfassung vom Kontext und den Gesamtzielen des Projekts
Carbonyl sulfide (COS) is the most abundant sulfur compound in our atmosphere with a mixing ratio of about 500 parts per trillion (ppt). Surprisingly, its global budget is poorly known, with recent updates of the dominant budget terms of more than 100%. The budget of COS is dominated by emissions from (tropical) oceans and anthropogenic production and uptake by the terrestrial biosphere, but significant uncertainties exist. Due to its long atmospheric lifetime of about 2 years, COS is transported to the stratosphere where its photochemical breakdown contributes to the formation of Stratospheric Sulphate Aerosols (SSA). Since these aerosols cool our climate, this is a first link between the sulfur cycle and climate.
A second link to climate is the uptake of COS by the terrestrial biosphere. COS has been suggested as a possible new constraint on the atmospheric carbon cycle, but only if some large caveats in our knowledge of its budget are resolved. If the COS budget is better understood, there are good prospects to use COS to constrain gross primary productivity (GPP) of terrestrial vegetation. Recent analyses of COS stored in ice cores link observed changes in COS to variations in GPP during the Holocene. Without a drastic reduction in COS source and sink uncertainties and their relationship with climate, these claims remain however rather speculative.
The two big scientific questions that are addressed in this research are:
1) What is the contribution of COS to the stratospheric sulphate aerosol layer?
2) Can the global budgets of COS and CO2 be reconciled, and what are the implications for terrestrial gross primary productivity?
This is important for society, because the impact of ongoing climate change on the carbon cycle is uncertain. Will large carbon reservoirs become unstable in a warming climate (positive feedback) or will the biosphere take up more carbon (negative feedback)?
Fundamental knowledge about these processes advances our understanding on how these intriguing mechanisms work.
The objectives of the proposed research are to:
1) Perform the first world-wide characterization of COS isotopologues by measuring seasonal, latitudinal, and altitude variations in troposphere and stratosphere
2) Measure COS gradients over the troposphere–stratosphere transition up to 30 km altitude using innovative AirCore sampling techniques
3) Investigate fractionation effects during soil and plant uptake in laboratory experiments
4) Develop the first model with capabilities to simulate COS-isotopologues and the coupled COS and CO2 cycles
5) Pioneer the use of satellite observations of COS and its isotopologues
6) Constrain the budgets of COS and CO2 using inverse modelling techniques employing surface measurements, satellite data, and new AirCore and isotopic COS measurements
A second link to climate is the uptake of COS by the terrestrial biosphere. COS has been suggested as a possible new constraint on the atmospheric carbon cycle, but only if some large caveats in our knowledge of its budget are resolved. If the COS budget is better understood, there are good prospects to use COS to constrain gross primary productivity (GPP) of terrestrial vegetation. Recent analyses of COS stored in ice cores link observed changes in COS to variations in GPP during the Holocene. Without a drastic reduction in COS source and sink uncertainties and their relationship with climate, these claims remain however rather speculative.
The two big scientific questions that are addressed in this research are:
1) What is the contribution of COS to the stratospheric sulphate aerosol layer?
2) Can the global budgets of COS and CO2 be reconciled, and what are the implications for terrestrial gross primary productivity?
This is important for society, because the impact of ongoing climate change on the carbon cycle is uncertain. Will large carbon reservoirs become unstable in a warming climate (positive feedback) or will the biosphere take up more carbon (negative feedback)?
Fundamental knowledge about these processes advances our understanding on how these intriguing mechanisms work.
The objectives of the proposed research are to:
1) Perform the first world-wide characterization of COS isotopologues by measuring seasonal, latitudinal, and altitude variations in troposphere and stratosphere
2) Measure COS gradients over the troposphere–stratosphere transition up to 30 km altitude using innovative AirCore sampling techniques
3) Investigate fractionation effects during soil and plant uptake in laboratory experiments
4) Develop the first model with capabilities to simulate COS-isotopologues and the coupled COS and CO2 cycles
5) Pioneer the use of satellite observations of COS and its isotopologues
6) Constrain the budgets of COS and CO2 using inverse modelling techniques employing surface measurements, satellite data, and new AirCore and isotopic COS measurements
Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse
Information on the project can be found on the project website: http://cos-ocs.eu(öffnet in neuem Fenster)
In WP1 we developed coupled COS–CO2 atmospheric transport model
Main results:
• Using the Simple Biosphere model SiB4, we have seen that the simulated COS soil flux can be very different depending on the biome. This is especially true for fertilized soils that are typically found in agricultural sites, where large emissions of COS are observed (Kooijmans et al., 2021)
• On a global scale, our SiB4 modifications decreased the modeled COS terrestrial biosphere sink from 922 GgS yr−1 in the original SiB4 to 753 GgS yr−1 in the updated version. The largest decrease in fluxes was driven by lower atmospheric COS mole fractions over regions with high productivity, which highlights the importance of accounting for variations in atmospheric COS mole fractions.
• Accounting for the temperature sensitivity of Carbonic Anhydrase (CA) for COS uptake leads to larger uptake at high latitudes, and smaller uptake in the tropics (Cho et al., 2023)
Other papers related to biosphere exchange of COS appeared (Kohonen et al., 2022; Kooijmans et al., 2019; Vesala et al., 2021).
An activity that was added to WP1 is the development of an interpretation framework of atmosphere-biosphere observations. In short, we developed a system to optimize parameters of a biosphere model using atmospheric observations, e.g. from a measurement tower. Peter Bosman, an external PhD linked to the COS-OCS project, developed this system (Bosman & Krol, 2023) and currently applies the method to observations of COS (and CO2).
Stratospheric removal has been implemented in the model in an early phase of the project, and has been reported in (Ma et al., 2021). We have implemented a new parameterization of the COS photolysis rate in the stratosphere to account for stratospheric removal and the impact on the COS isotopoloques (Nagori et al., 2022). We implemented isotopes in the TM5 model. First results indicate that, while the observed mixing ratios are relatively well reproduced by the model, the model shows very low variability in the isotopologues. In contrast, measurements show much more variability and likely explanation is that the isotope source signatures are much more variable than currently assumed. There might also be a role of chemical transformations in the atmosphere. A large fraction of the COS in the atmosphere comes from oxidation of CS2, and possibly also DMS (Jernigan et al., 2022). Little is known about the isotopic composition of these compounds and possible fractionation effects in their oxidation to COS. Our model, which is the first model that is able to simulate COS isotopologues including its precursors, offers a good starting point for further investigation of these issues. These findings have been presented during the 3rd international COS workshop in Utrecht (https://www2.projects.science.uu.nl/tm5/COS_workshop/maartenkrol.pdf(öffnet in neuem Fenster) user: cos, password: ocs).
We have evaluated our model results against atmospheric observations in (Ma et al., 2021b).Moreover, during the project we launched, together with our French co-workers an intercomparison. Two papers are now produced (Ma, Remaud, et al., 2023; Remaud et al., 2023). In these papers we compare COS simulations of six models against atmospheric observations from the NOAA surface network, the NOAA aircraft program, and against HIPPO and Atom campaigns. The main outcome of this exercise is that two sets of optimized surface fluxes (Ma et al., 2021; Remaud et al., 2022) perform much better in reproducing atmospheric observations than the set of prior fluxes that was known at the start of the COS-OCS project. Hence, we have learned where the surface fluxes of COS need to be adjusted. This confirms the missing tropical source, and the need for higher COS uptake at high Northern latitudes. These results have been presented at the 3rd international COS workshop in Utrecht (2022) (http://cos-ocs.eu/3rd-international-cos-works.html(öffnet in neuem Fenster) To access presentations: user: cos, password: ocs).
In WP2 we developed a COS-isotopologue measurement method
This activity has been conducted in the Utrecht lab and results have been published (Baartman et al., 2022).A new system was developed for measuring sulfur isotopes δ33S and δ34S from atmospheric carbonyl sulfide (COS) on small air samples of several liters, using pre-concentration and gas chromatography – isotope ratio mass spectrometry (GC-IRMS). For a 4 liter sample at ambient COS mixing ratio, ~500 parts per trillion (ppt), we obtain a reproducibility error of 2.1 ‰ for δ 33S and 0.4 ‰ for δ 34 S. After applying corrections, the uncertainty for an individual ambient air sample measurement is 2.5 ‰ for δ 33S and 0.9 ‰ for δ 34S. The ability to measure small samples allows application to a global-scale sampling program with limited logistical effort.
To illustrate the application of this newly developed system, we presented a timeseries of ambient air measurements, during the fall and winter of 2020 and 2021 in Utrecht, the Netherlands (Baartman et al., 2022).The observed background values were δ33S = 1.0 ± 3.4 ‰ and δ34S = 15.5 ± 0.8 ‰ (VCDT). The maximum observed COS mixing ratios was only 620 ppt. This, in combination with the relatively high δ34S suggests that the Netherlands receives little COS-containing anthropogenic emissions. Additionally, we presented the results of samples from a highway tunnel to characterize vehicle COS emissions and isotopic composition. The vehicle emissions were small, with COS/CO2 being 0.4 ppt/ppm; the isotopic signatures were depleted relatively to background atmospheric COS, in line with anthropogenic emissions being relatively light compared to e.g. ocean emissions.
Due to COVID restrictions, we did not succeed in setting up a global measurement network. Contacting stations and setting up transport of samples proved very difficult. However, we managed to embark on an exciting opportunity mission: HEMERA (https://www.hemera-h2020.eu(öffnet in neuem Fenster)). After being postponed several times, there was a successful launch in August 2021 (Blog: https://twin-hemera-2021.sites.uu.nl(öffnet in neuem Fenster)).
Currently, we are in the process of assessing the quality of the data. Unfortunately, we found that COS was not stable in the canisters (COS mole fractions have been increasing over time for unknown reasons). We analyzed the samples for isotopes in the Utrecht lab, in order to have the first stratospheric COS isotopologue measurements. With the new instrument that we purchased (partly from the COS-OCS project), we have measured – next to δ33S and δ34S in COS – also δ13C. Unfortunately, the unstable COS in the canisters likely invalidates the measurements.
We also measured δ34S-COS (old machine, no δ13C-COS) from samples that were collected during the Stratoclim campaign in 2017 (Bucci et al., 2020). These samples proved to be stable for COS, and we have measured δ34S-COS & δ33S-COS on the samples. Currently, these measurements are part of the thesis by Sophie Baartman (Utrecht University).
Another activity that was conducted by our Groningen PhD (Alessandro Zanchetta) learned us more about COS sources (Zanchetta et al., 2023). In this paper, we infer the regional sources and sinks of COS using continuous in-situ mole fraction profile measurements of COS along the 60-m tall Lutjewad tower (1 m a.s.l. 53°24'N, 6°21'E) in the Netherlands. To identify potential sources that caused the observed enhancements of COS mole fractions at Lutjewad, both discrete flask samples and in-situ measurements in the province of Groningen were made on a mobile van using a quantum cascade laser spectrometer (QCLS). We identified and quantified several COS sources, including biodigesters, sugar production facilities, and silicon carbide production facilities in the province of Groningen. Moreover, the simulation results show that the observed COS enhancements can be partially explained by known industrial sources of COS and CS2, in particular from the Ruhr valley (51.5°N, 7.2°E) and Antwerp (51.2° N, 4.4° E) areas. These results are valuable for improving our understanding of the sources and sinks of COS, contributing to the use of COS as a tracer for GPP.
As mentioned above, COS measurements were realized deploying a Quantum Cascade Laser Spectrometer (QCLS, Aerodyne Research Inc., MA, USA, model TILDAS-C, acquired on the COS-OCS project). The QCLS is a spectrometer working in the mid-IR frequency range and measures CH4, N¬2O, H2O, COS, CO2 and CO simultaneously. This instrument measures COS with a precision of about 20 ppt (1, at 1Hz). A front-end system was developed to make the QCLS suitable for AirCore’s measurements.
AirCore measurements make it possible to collect continuous stratospheric air samples at a relatively low cost. AirCore COS measurements were realized during the RINGO campaign (Trainou, France, 47°58' N, 2°6' E), in June 2019 and during the HEMERA campaign (Kiruna, Sweden, 67°53' N, 21°04' E) in August 2021. During these campaigns, AirCore’s successfully collected (COS) stratospheric samples on balloon-borne stratospheric flights, which were then measured on the QCLS. The results are currently being compared with modelled results retrieved from the TM5-4DVAR model, as well as remote sensing observations obtained from the ACE-FTS satellite.
In cooperation with the plant sciences group at Wageningen university, we performed measurements in plant chambers. In their lab we installed the Quantum Cascade Laser Spectrometer (QCLS, Aerodyne Research Inc., funded by COS-OCS). The CO2 leaf assimilation and plant evaporation were also sampled with a Licor (LI6800).
The lab contains a flow-through plant chamber to measure CO2 and COS exchange with an entire plant (with the soil sealed off). We performed three experiments in which we studied (1) the response of COS and CO2 uptake to stomatal closure under constant temperature, (2) the temperature dependence of the COS and CO2 leaf uptake under constant gs, and (3) the change of compensation points with temperature. The experiments were performed with sunflower plants (Helianthus Annuus Sunsation), grown in a local plant nursery. Experiments 1 and 2 were repeated in three different sunflower plants on three different days, and experiment 3 was performed once, also in a sunflower plant. During these experiments, samples were taken on which isotopic analysis (13C, 33,34S) were performed. We also measured a C4 plant (Papyrus).
In a later stage, we also conducted experiments on single leaves (without taking isotopic samples). Currently, we are still in the stage of analyzing the results and writing up the results. One publication that is in preparation is on the isotopic analysis of plant uptake (part of the Thesis of Sophie Baartman). Another publication that is in preparation is by Ara Cho (PhD Wageningen university). She will focus on the combined uptake of COS and CO2 (leaf relative uptake) and the interpretation using a simple model. Results have been presented on the 3rd international COS workshop in Utrecht (http://cos-ocs.eu/3rd-international-cos-works.html(öffnet in neuem Fenster) user: cos, password: ocs).
In WP3 we performed Inverse modelling of the coupled COS and CO2 budgets
The first results of the implementation of COS in the TM5-4DVAR model is described in (Ma et al., 2021). Our implementation of COS in the 4DVAR system accounts for the oxidation of COS from CS2 and DMS. Given the current discussion on possible new production pathways of COS from DMS (Jernigan et al., 2022), this has been a good choice. We are the first group to have a 4DVAR implementation of COS, and we have optimized emissions in the period 2000-2012. By optimizing an “Unknown” COS flux at the surface we confirmed that a COS source is needed in the tropics and a sink at high Northern latitude. We compared our inverse modelling results to observations from the HIPPO campaign, the NOAA aircraft sampling program, and with satellite data from MIPAS and ACE-FTS. A major finding of this study was that the inversion is generally data-poor, meaning that there are not enough observations to constrain individual source categories.
Results of our inversion have been used by other research groups (Parazoo et al., 2021) and our modelling efforts lead to a TRANSCOM model intercomparison. In this intercomparison, seven models used a pre-scribed set of fluxes (including our optimized fluxes) to simulate global COS distributions. Propagating two sets of optimized COS fluxes in seven Atmospheric Transport Models leads to simulations in agreement with independent observations. Main conclusions of this intercomparison are (Ma et al., 2023; Remaud et al., 2023):
1. The optimized fluxes derived from TM5-4DVAR and LMDz inversions show similar spatial distribution while TM5 flux demonstrates larger seasonal cycle.
2. The optimized fluxes improved the simulations over a control scenario, and well match aircraft data HIPPO and ATOM and airborne platform.
3. Comparisons to airborne observations reveal COS drawdown effects likely caused by plant uptake from the NH continent over the Pacific and from the Amazon over the Atlantic ocean.
4. Models with weak vertical mixing using fluxes optimized with the fast-mixing TM5 model overestimate the COS seasonal amplitude at high latitudes.
Another follow-on activity is that we started to assimilate MIPAS observations in our TM5-4DVAR framework. Although other studies used MIPAS data, e.g. to estimate Gross Primary Productivity from the Amazon region (Stinecipher et al., 2022), we performed a formal inversion in which both NOAA observations and MIPAS data are assimilated. The inferred terrestrial biosphere fluxes show improvements when we assimilate MIPAS data. In NOAA only inversions, biosphere flux optimized showed unrealistic positive fluxes, and in NOAA+MIPAS inversions, the optimized biosphere flux remained negative. In all inversions we performed, biosphere fluxes get reduced compared to the prior, which implies that the inverse system reduces GPP, in line with findings of (Stinecipher et al., 2022). This work is now available in pre-print (Ma, Kooijmans, et al., 2023)
All the work in activity 3.1 will be part of a PhD thesis that will be defended in 2023 (Jin Ma).
Although out isotope model has been constructed, we did not use isotope observations yet to formally constrain the COS budget. Aircore observations are currently being compared to the model output and results look promising. However, we learned that the data are better suited as an a-posteriori (= model with optimized fluxes) check on the improvements. The joint COS-CO2 inversion work is still in progress.
In WP1 we developed coupled COS–CO2 atmospheric transport model
Main results:
• Using the Simple Biosphere model SiB4, we have seen that the simulated COS soil flux can be very different depending on the biome. This is especially true for fertilized soils that are typically found in agricultural sites, where large emissions of COS are observed (Kooijmans et al., 2021)
• On a global scale, our SiB4 modifications decreased the modeled COS terrestrial biosphere sink from 922 GgS yr−1 in the original SiB4 to 753 GgS yr−1 in the updated version. The largest decrease in fluxes was driven by lower atmospheric COS mole fractions over regions with high productivity, which highlights the importance of accounting for variations in atmospheric COS mole fractions.
• Accounting for the temperature sensitivity of Carbonic Anhydrase (CA) for COS uptake leads to larger uptake at high latitudes, and smaller uptake in the tropics (Cho et al., 2023)
Other papers related to biosphere exchange of COS appeared (Kohonen et al., 2022; Kooijmans et al., 2019; Vesala et al., 2021).
An activity that was added to WP1 is the development of an interpretation framework of atmosphere-biosphere observations. In short, we developed a system to optimize parameters of a biosphere model using atmospheric observations, e.g. from a measurement tower. Peter Bosman, an external PhD linked to the COS-OCS project, developed this system (Bosman & Krol, 2023) and currently applies the method to observations of COS (and CO2).
Stratospheric removal has been implemented in the model in an early phase of the project, and has been reported in (Ma et al., 2021). We have implemented a new parameterization of the COS photolysis rate in the stratosphere to account for stratospheric removal and the impact on the COS isotopoloques (Nagori et al., 2022). We implemented isotopes in the TM5 model. First results indicate that, while the observed mixing ratios are relatively well reproduced by the model, the model shows very low variability in the isotopologues. In contrast, measurements show much more variability and likely explanation is that the isotope source signatures are much more variable than currently assumed. There might also be a role of chemical transformations in the atmosphere. A large fraction of the COS in the atmosphere comes from oxidation of CS2, and possibly also DMS (Jernigan et al., 2022). Little is known about the isotopic composition of these compounds and possible fractionation effects in their oxidation to COS. Our model, which is the first model that is able to simulate COS isotopologues including its precursors, offers a good starting point for further investigation of these issues. These findings have been presented during the 3rd international COS workshop in Utrecht (https://www2.projects.science.uu.nl/tm5/COS_workshop/maartenkrol.pdf(öffnet in neuem Fenster) user: cos, password: ocs).
We have evaluated our model results against atmospheric observations in (Ma et al., 2021b).Moreover, during the project we launched, together with our French co-workers an intercomparison. Two papers are now produced (Ma, Remaud, et al., 2023; Remaud et al., 2023). In these papers we compare COS simulations of six models against atmospheric observations from the NOAA surface network, the NOAA aircraft program, and against HIPPO and Atom campaigns. The main outcome of this exercise is that two sets of optimized surface fluxes (Ma et al., 2021; Remaud et al., 2022) perform much better in reproducing atmospheric observations than the set of prior fluxes that was known at the start of the COS-OCS project. Hence, we have learned where the surface fluxes of COS need to be adjusted. This confirms the missing tropical source, and the need for higher COS uptake at high Northern latitudes. These results have been presented at the 3rd international COS workshop in Utrecht (2022) (http://cos-ocs.eu/3rd-international-cos-works.html(öffnet in neuem Fenster) To access presentations: user: cos, password: ocs).
In WP2 we developed a COS-isotopologue measurement method
This activity has been conducted in the Utrecht lab and results have been published (Baartman et al., 2022).A new system was developed for measuring sulfur isotopes δ33S and δ34S from atmospheric carbonyl sulfide (COS) on small air samples of several liters, using pre-concentration and gas chromatography – isotope ratio mass spectrometry (GC-IRMS). For a 4 liter sample at ambient COS mixing ratio, ~500 parts per trillion (ppt), we obtain a reproducibility error of 2.1 ‰ for δ 33S and 0.4 ‰ for δ 34 S. After applying corrections, the uncertainty for an individual ambient air sample measurement is 2.5 ‰ for δ 33S and 0.9 ‰ for δ 34S. The ability to measure small samples allows application to a global-scale sampling program with limited logistical effort.
To illustrate the application of this newly developed system, we presented a timeseries of ambient air measurements, during the fall and winter of 2020 and 2021 in Utrecht, the Netherlands (Baartman et al., 2022).The observed background values were δ33S = 1.0 ± 3.4 ‰ and δ34S = 15.5 ± 0.8 ‰ (VCDT). The maximum observed COS mixing ratios was only 620 ppt. This, in combination with the relatively high δ34S suggests that the Netherlands receives little COS-containing anthropogenic emissions. Additionally, we presented the results of samples from a highway tunnel to characterize vehicle COS emissions and isotopic composition. The vehicle emissions were small, with COS/CO2 being 0.4 ppt/ppm; the isotopic signatures were depleted relatively to background atmospheric COS, in line with anthropogenic emissions being relatively light compared to e.g. ocean emissions.
Due to COVID restrictions, we did not succeed in setting up a global measurement network. Contacting stations and setting up transport of samples proved very difficult. However, we managed to embark on an exciting opportunity mission: HEMERA (https://www.hemera-h2020.eu(öffnet in neuem Fenster)). After being postponed several times, there was a successful launch in August 2021 (Blog: https://twin-hemera-2021.sites.uu.nl(öffnet in neuem Fenster)).
Currently, we are in the process of assessing the quality of the data. Unfortunately, we found that COS was not stable in the canisters (COS mole fractions have been increasing over time for unknown reasons). We analyzed the samples for isotopes in the Utrecht lab, in order to have the first stratospheric COS isotopologue measurements. With the new instrument that we purchased (partly from the COS-OCS project), we have measured – next to δ33S and δ34S in COS – also δ13C. Unfortunately, the unstable COS in the canisters likely invalidates the measurements.
We also measured δ34S-COS (old machine, no δ13C-COS) from samples that were collected during the Stratoclim campaign in 2017 (Bucci et al., 2020). These samples proved to be stable for COS, and we have measured δ34S-COS & δ33S-COS on the samples. Currently, these measurements are part of the thesis by Sophie Baartman (Utrecht University).
Another activity that was conducted by our Groningen PhD (Alessandro Zanchetta) learned us more about COS sources (Zanchetta et al., 2023). In this paper, we infer the regional sources and sinks of COS using continuous in-situ mole fraction profile measurements of COS along the 60-m tall Lutjewad tower (1 m a.s.l. 53°24'N, 6°21'E) in the Netherlands. To identify potential sources that caused the observed enhancements of COS mole fractions at Lutjewad, both discrete flask samples and in-situ measurements in the province of Groningen were made on a mobile van using a quantum cascade laser spectrometer (QCLS). We identified and quantified several COS sources, including biodigesters, sugar production facilities, and silicon carbide production facilities in the province of Groningen. Moreover, the simulation results show that the observed COS enhancements can be partially explained by known industrial sources of COS and CS2, in particular from the Ruhr valley (51.5°N, 7.2°E) and Antwerp (51.2° N, 4.4° E) areas. These results are valuable for improving our understanding of the sources and sinks of COS, contributing to the use of COS as a tracer for GPP.
As mentioned above, COS measurements were realized deploying a Quantum Cascade Laser Spectrometer (QCLS, Aerodyne Research Inc., MA, USA, model TILDAS-C, acquired on the COS-OCS project). The QCLS is a spectrometer working in the mid-IR frequency range and measures CH4, N¬2O, H2O, COS, CO2 and CO simultaneously. This instrument measures COS with a precision of about 20 ppt (1, at 1Hz). A front-end system was developed to make the QCLS suitable for AirCore’s measurements.
AirCore measurements make it possible to collect continuous stratospheric air samples at a relatively low cost. AirCore COS measurements were realized during the RINGO campaign (Trainou, France, 47°58' N, 2°6' E), in June 2019 and during the HEMERA campaign (Kiruna, Sweden, 67°53' N, 21°04' E) in August 2021. During these campaigns, AirCore’s successfully collected (COS) stratospheric samples on balloon-borne stratospheric flights, which were then measured on the QCLS. The results are currently being compared with modelled results retrieved from the TM5-4DVAR model, as well as remote sensing observations obtained from the ACE-FTS satellite.
In cooperation with the plant sciences group at Wageningen university, we performed measurements in plant chambers. In their lab we installed the Quantum Cascade Laser Spectrometer (QCLS, Aerodyne Research Inc., funded by COS-OCS). The CO2 leaf assimilation and plant evaporation were also sampled with a Licor (LI6800).
The lab contains a flow-through plant chamber to measure CO2 and COS exchange with an entire plant (with the soil sealed off). We performed three experiments in which we studied (1) the response of COS and CO2 uptake to stomatal closure under constant temperature, (2) the temperature dependence of the COS and CO2 leaf uptake under constant gs, and (3) the change of compensation points with temperature. The experiments were performed with sunflower plants (Helianthus Annuus Sunsation), grown in a local plant nursery. Experiments 1 and 2 were repeated in three different sunflower plants on three different days, and experiment 3 was performed once, also in a sunflower plant. During these experiments, samples were taken on which isotopic analysis (13C, 33,34S) were performed. We also measured a C4 plant (Papyrus).
In a later stage, we also conducted experiments on single leaves (without taking isotopic samples). Currently, we are still in the stage of analyzing the results and writing up the results. One publication that is in preparation is on the isotopic analysis of plant uptake (part of the Thesis of Sophie Baartman). Another publication that is in preparation is by Ara Cho (PhD Wageningen university). She will focus on the combined uptake of COS and CO2 (leaf relative uptake) and the interpretation using a simple model. Results have been presented on the 3rd international COS workshop in Utrecht (http://cos-ocs.eu/3rd-international-cos-works.html(öffnet in neuem Fenster) user: cos, password: ocs).
In WP3 we performed Inverse modelling of the coupled COS and CO2 budgets
The first results of the implementation of COS in the TM5-4DVAR model is described in (Ma et al., 2021). Our implementation of COS in the 4DVAR system accounts for the oxidation of COS from CS2 and DMS. Given the current discussion on possible new production pathways of COS from DMS (Jernigan et al., 2022), this has been a good choice. We are the first group to have a 4DVAR implementation of COS, and we have optimized emissions in the period 2000-2012. By optimizing an “Unknown” COS flux at the surface we confirmed that a COS source is needed in the tropics and a sink at high Northern latitude. We compared our inverse modelling results to observations from the HIPPO campaign, the NOAA aircraft sampling program, and with satellite data from MIPAS and ACE-FTS. A major finding of this study was that the inversion is generally data-poor, meaning that there are not enough observations to constrain individual source categories.
Results of our inversion have been used by other research groups (Parazoo et al., 2021) and our modelling efforts lead to a TRANSCOM model intercomparison. In this intercomparison, seven models used a pre-scribed set of fluxes (including our optimized fluxes) to simulate global COS distributions. Propagating two sets of optimized COS fluxes in seven Atmospheric Transport Models leads to simulations in agreement with independent observations. Main conclusions of this intercomparison are (Ma et al., 2023; Remaud et al., 2023):
1. The optimized fluxes derived from TM5-4DVAR and LMDz inversions show similar spatial distribution while TM5 flux demonstrates larger seasonal cycle.
2. The optimized fluxes improved the simulations over a control scenario, and well match aircraft data HIPPO and ATOM and airborne platform.
3. Comparisons to airborne observations reveal COS drawdown effects likely caused by plant uptake from the NH continent over the Pacific and from the Amazon over the Atlantic ocean.
4. Models with weak vertical mixing using fluxes optimized with the fast-mixing TM5 model overestimate the COS seasonal amplitude at high latitudes.
Another follow-on activity is that we started to assimilate MIPAS observations in our TM5-4DVAR framework. Although other studies used MIPAS data, e.g. to estimate Gross Primary Productivity from the Amazon region (Stinecipher et al., 2022), we performed a formal inversion in which both NOAA observations and MIPAS data are assimilated. The inferred terrestrial biosphere fluxes show improvements when we assimilate MIPAS data. In NOAA only inversions, biosphere flux optimized showed unrealistic positive fluxes, and in NOAA+MIPAS inversions, the optimized biosphere flux remained negative. In all inversions we performed, biosphere fluxes get reduced compared to the prior, which implies that the inverse system reduces GPP, in line with findings of (Stinecipher et al., 2022). This work is now available in pre-print (Ma, Kooijmans, et al., 2023)
All the work in activity 3.1 will be part of a PhD thesis that will be defended in 2023 (Jin Ma).
Although out isotope model has been constructed, we did not use isotope observations yet to formally constrain the COS budget. Aircore observations are currently being compared to the model output and results look promising. However, we learned that the data are better suited as an a-posteriori (= model with optimized fluxes) check on the improvements. The joint COS-CO2 inversion work is still in progress.
Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)
Overall, our efforts within the COS-OCS program have led to substantial new insights into the COS budget, and this effort has been picked up by the community (e.g. (Ma et al., 2021) had 33 google scholar citations on 29-11-2023, and (Kooijmans et al., 2021) received 27 citations).
Most of the proposed work has been performed, which resulted in roughly 20 publications, two international workshops, participation in a large international campaign, and a global model intercomparison project.
Much of the work is still in progress, and we expect three PhD defences (one took place in October 2022).
Within the course of the COS-OCS project our efforts have significantly contributed to the field. Research into COS has a relatively small number of active researchers, based mainly on a paper that appeared after the first international COS workshop (Whelan et al., 2018) that appeared at the start of our project. We had the opportunity to strengthen the community, e.g. by attending the second workshop in Austria (keynote presentation by the PI) and organizing the third workshop. Specifically, our modelling work has advanced the field with the organization of a model intercomparison. Moreover, the PI was invited to a UK workshop in March 2023 to present results. Our modelling work on the biosphere model SiB4 also received quite some attention. Our isotope measurement system has been published (Baartman et al., 2022) but the applications of the system on stratospheric COS removal and plant uptake are still in writing. Hence, this work received less attention up to now.
None of the results may be classified as highly unexpected. However, based on our results, we speculate that there is a missing COS from oceanic DMS (Jernigan et al., 2022), something that was discussed at length in the third international COS workshop in Utrecht (http://cos-ocs.eu/3rd-international-cos-works.html(öffnet in neuem Fenster)).
In conclusion, we had the opportunity to find connections to an active research community. We benefitted from their friendly and open attitude, and were able to contribute with our research to ongoing activities within the community.
References:
Baartman, S. L., Krol, M. C., Röckmann, T., Hattori, S., Kamezaki, K., Yoshida, N., & Popa, M. E. (2022). A GC-IRMS method for measuring sulfur isotope ratios of carbonyl sulfide from small air samples. Open Research Europe, 1(March), 105. https://doi.org/10.12688/openreseurope.13875.2(öffnet in neuem Fenster)
Bosman, P. J. M., & Krol, M. C. (2023). ICLASS 1.1 a variational Inverse modelling framework for the Chemistry Land-surface Atmosphere Soil Slab model: description, validation, and application. Geoscientific Model Development, 16(1), 47–74. https://doi.org/10.5194/gmd-16-47-2023(öffnet in neuem Fenster)
Bucci, S., Legras, B., Sellitto, P., D’Amato, F., Viciani, S., Montori, A., Chiarugi, A., Ravegnani, F., Ulanovsky, A., Cairo, F., & Stroh, F. (2020). Deep-convective influence on the upper troposphere-lower stratosphere composition in the Asian monsoon anticyclone region: 2017 StratoClim campaign results. Atmospheric Chemistry and Physics, 20(20), 12193–12210. https://doi.org/10.5194/acp-20-12193-2020(öffnet in neuem Fenster)
Cho, A., Kooijmans, L. M. J., Kohonen, K. M., Wehr, R., & Krol, M. C. (2023). Optimizing the carbonic anhydrase temperature response and stomatal conductance of carbonyl sulfide leaf uptake in the Simple Biosphere model (SiB4). Biogeosciences, 20(13), 2573–2594. https://doi.org/10.5194/BG-20-2573-2023(öffnet in neuem Fenster)
Jernigan, C. M., Fite, C. H., Vereecken, L., Berkelhammer, M. B., Rollins, A. W., Rickly, P. S., Novelli, A., Taraborrelli, D., Holmes, C. D., & Bertram, T. H. (2022a). Efficient production of carbonyl sulfide in the low‐NO x oxidation of dimethyl sulfide . Geophysical Research Letters, x, 1–11. https://doi.org/10.1029/2021gl096838(öffnet in neuem Fenster)
Kohonen, K., Dewar, R., Tramontana, G., Mauranen, A., Kolari, P., Kooijmans, L. M. J., Papale, D., Vesala, T., & Mammarella, I. (2022). Intercomparison of methods to estimate GPP based on CO 2 and COS flux measurements. February, 1–30.
Kooijmans, L. M. J., Cho, A., Ma, J., Kaushik, A., Haynes, K. D., Baker, I., Luijkx, I. T., Groenink, M., Peters, W., Miller, J. B., Berry, J. A., Ogée, J., Meredith, L. K., Sun, W., Kohonen, K. M., Vesala, T., Mammarella, I., Chen, H., Spielmann, F. M., … Krol, M. (2021). Evaluation of carbonyl sulfide biosphere exchange in the Simple Biosphere Model (SiB4). Biogeosciences, 18(24), 6547–6565. https://doi.org/10.5194/bg-18-6547-2021(öffnet in neuem Fenster)
Kooijmans, L. M. J., Sun, W., Aalto, J., Erkkilä, K.-M. Maseyk, K., Seibt, U., Vesala, T., Mammarella, I., & Chen, H. (2019). Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis. Proceedings of the National Academy of Sciences, 105, 201807600. https://doi.org/10.1073/pnas.1807600116(öffnet in neuem Fenster)
Ma, J., Kooijmans, L. M. J., Cho, A., Montzka, S. A., Glatthor, N., Worden, J. R., Kuai, L., Atlas, E. L., & Krol, M. C. (2021). Inverse modelling of carbonyl sulfide: implementation, evaluation and implications for the global budget. Atmospheric Chemistry and Physcis, 21(5), 3507–3529. https://acp.copernicus.org/articles/21/3507/2021/acp-21-3507-2021.pdf(öffnet in neuem Fenster)
Ma, J., Kooijmans, L. M. J., Glatthor, N., Montzka, S. A., Von Hobe, M., Röckmann, T., & Krol, M. C. (2023). Combined assimilation of NOAA surface and MIPAS satellite observations to constrain the global budget of carbonyl sulfide. Egusphere. https://doi.org/10.5194/egusphere-2023-1133(öffnet in neuem Fenster)
Ma, J., Remaud, M., Peylin, P., Patra, P., Niwa, Y., Rodenbeck, C., Cartwright, M., Harrison, J. J., Chipperfield, M. P., Pope, R. J., Wilson, C., Belviso, S., Montzka, S. A., Vimont, I., Moore, F., Atlas, E. L., Schwartz, E., & Krol, M. C. (2023). Intercomparison of atmospheric carbonyl sulfide (TransCom‐COS; Part Two): Evaluation of optimized fluxes using ground‐based and aircraft observations. Journal of Geophysical Research: Atmospheres. https://doi.org/10.1029/2023jd039198(öffnet in neuem Fenster)
Nagori, J., Nechita-bând, N., Danielache, S. O., & Shinkai, M. (2022). Modelling the atmospheric 34 S-sulfur budget in a column model under volcanically quiescent conditions. 1991(January), 1–30.
Parazoo, N. C., Bowman, K. W., Baier, B. C., Liu, J., Lee, M., Kuai, L., Shiga, Y., Baker, I., Whelan, M. E., Feng, S., Krol, M., Sweeney, C., Runkle, B. R., Tajfar, E., & Davis, K. J. (2021). Covariation of Airborne Biogenic Tracers (CO2, COS, and CO) Supports Stronger Than Expected Growing Season Photosynthetic Uptake in the Southeastern US. Global Biogeochemical Cycles, 35(10). https://doi.org/10.1029/2021GB006956(öffnet in neuem Fenster)
Remaud, M., Chevallier, F., Maignan, F., Belviso, S., Berchet, A., Parouffe, A., Abadie, C., Bacour, C., Lennartz, S., & Peylin, P. (2022). Plant gross primary production, plant respiration and carbonyl sulfide emissions over the globe inferred by atmospheric inverse modelling. Atmospheric Chemistry and Physics, 22(4), 2525–2552. https://doi.org/10.5194/acp-22-2525-2022(öffnet in neuem Fenster)
Remaud, M., Ma, J., Krol, M., Abadie, C., Cartwright, M. P., Patra, P., Niwa, Y., Rodenbeck, C., Belviso, S., Kooijmans, L., Lennartz, S., Maignan, F., Chevallier, F., Chipperfield, M. P., Pope, R. J., Harrison, J. J., Vimont, I., Wilson, C., & Peylin, P. (2023). Intercomparison of Atmospheric Carbonyl Sulfide (TransCom-COS; Part One): Evaluating the Impact of Transport and Emissions on Tropospheric Variability Using Ground-Based and Aircraft Data. Journal of Geophysical Research: Atmospheres, 128(6). https://doi.org/10.1029/2022JD037817(öffnet in neuem Fenster)
Vesala, T., Kohonen, K.-M. Praplan, A., Kooijmans, L., Foltýnová, L., Kolari, P., Kulmala, M., Bäck, J., Nelson, D., Yakir, D., Zahniser, M., & Mammarella, I. (2021). Long-term fluxes of carbonyl sulfide and their seasonality and interannual variability in a boreal forest. Atmospheric Chemistry and Physics, August, 1–19. https://doi.org/10.5194/acp-2021-721(öffnet in neuem Fenster)
Whelan, M. E., Lennartz, S. T., Gimeno, T. E., Wehr, R., Wohlfahrt, G., Wang, Y., Kooijmans, L. M. J., Hilton, T. W., Belviso, S., Peylin, P., Commane, R., Sun, W., Chen, H., Kuai, L., Mammarella, I., Maseyk, K., Berkelhammer, M., Li, K. F., Yakir, D., … Campbell, J. E. (2018). Reviews and syntheses: Carbonyl sulfide as a~multi-scale tracer for carbon and water cycles. Biogeosciences, 15(12), 3625–3657. https://doi.org/10.5194/bg-15-3625-2018(öffnet in neuem Fenster)
Zanchetta, A., Kooijmans, L. M. J., van Heuven, S., Scifo, A., Scheeren, H. A., Mammarella, I., Karstens, U., Ma, J., Krol, M., & Chen, H. (2023). Sources and sinks of carbonyl sulfide inferred from tower and mobile atmospheric observations in the Netherlands. Biogeosciences, 20(16), 3539–3553. https://doi.org/10.5194/BG-20-3539-2023(öffnet in neuem Fenster)
Most of the proposed work has been performed, which resulted in roughly 20 publications, two international workshops, participation in a large international campaign, and a global model intercomparison project.
Much of the work is still in progress, and we expect three PhD defences (one took place in October 2022).
Within the course of the COS-OCS project our efforts have significantly contributed to the field. Research into COS has a relatively small number of active researchers, based mainly on a paper that appeared after the first international COS workshop (Whelan et al., 2018) that appeared at the start of our project. We had the opportunity to strengthen the community, e.g. by attending the second workshop in Austria (keynote presentation by the PI) and organizing the third workshop. Specifically, our modelling work has advanced the field with the organization of a model intercomparison. Moreover, the PI was invited to a UK workshop in March 2023 to present results. Our modelling work on the biosphere model SiB4 also received quite some attention. Our isotope measurement system has been published (Baartman et al., 2022) but the applications of the system on stratospheric COS removal and plant uptake are still in writing. Hence, this work received less attention up to now.
None of the results may be classified as highly unexpected. However, based on our results, we speculate that there is a missing COS from oceanic DMS (Jernigan et al., 2022), something that was discussed at length in the third international COS workshop in Utrecht (http://cos-ocs.eu/3rd-international-cos-works.html(öffnet in neuem Fenster)).
In conclusion, we had the opportunity to find connections to an active research community. We benefitted from their friendly and open attitude, and were able to contribute with our research to ongoing activities within the community.
References:
Baartman, S. L., Krol, M. C., Röckmann, T., Hattori, S., Kamezaki, K., Yoshida, N., & Popa, M. E. (2022). A GC-IRMS method for measuring sulfur isotope ratios of carbonyl sulfide from small air samples. Open Research Europe, 1(March), 105. https://doi.org/10.12688/openreseurope.13875.2(öffnet in neuem Fenster)
Bosman, P. J. M., & Krol, M. C. (2023). ICLASS 1.1 a variational Inverse modelling framework for the Chemistry Land-surface Atmosphere Soil Slab model: description, validation, and application. Geoscientific Model Development, 16(1), 47–74. https://doi.org/10.5194/gmd-16-47-2023(öffnet in neuem Fenster)
Bucci, S., Legras, B., Sellitto, P., D’Amato, F., Viciani, S., Montori, A., Chiarugi, A., Ravegnani, F., Ulanovsky, A., Cairo, F., & Stroh, F. (2020). Deep-convective influence on the upper troposphere-lower stratosphere composition in the Asian monsoon anticyclone region: 2017 StratoClim campaign results. Atmospheric Chemistry and Physics, 20(20), 12193–12210. https://doi.org/10.5194/acp-20-12193-2020(öffnet in neuem Fenster)
Cho, A., Kooijmans, L. M. J., Kohonen, K. M., Wehr, R., & Krol, M. C. (2023). Optimizing the carbonic anhydrase temperature response and stomatal conductance of carbonyl sulfide leaf uptake in the Simple Biosphere model (SiB4). Biogeosciences, 20(13), 2573–2594. https://doi.org/10.5194/BG-20-2573-2023(öffnet in neuem Fenster)
Jernigan, C. M., Fite, C. H., Vereecken, L., Berkelhammer, M. B., Rollins, A. W., Rickly, P. S., Novelli, A., Taraborrelli, D., Holmes, C. D., & Bertram, T. H. (2022a). Efficient production of carbonyl sulfide in the low‐NO x oxidation of dimethyl sulfide . Geophysical Research Letters, x, 1–11. https://doi.org/10.1029/2021gl096838(öffnet in neuem Fenster)
Kohonen, K., Dewar, R., Tramontana, G., Mauranen, A., Kolari, P., Kooijmans, L. M. J., Papale, D., Vesala, T., & Mammarella, I. (2022). Intercomparison of methods to estimate GPP based on CO 2 and COS flux measurements. February, 1–30.
Kooijmans, L. M. J., Cho, A., Ma, J., Kaushik, A., Haynes, K. D., Baker, I., Luijkx, I. T., Groenink, M., Peters, W., Miller, J. B., Berry, J. A., Ogée, J., Meredith, L. K., Sun, W., Kohonen, K. M., Vesala, T., Mammarella, I., Chen, H., Spielmann, F. M., … Krol, M. (2021). Evaluation of carbonyl sulfide biosphere exchange in the Simple Biosphere Model (SiB4). Biogeosciences, 18(24), 6547–6565. https://doi.org/10.5194/bg-18-6547-2021(öffnet in neuem Fenster)
Kooijmans, L. M. J., Sun, W., Aalto, J., Erkkilä, K.-M. Maseyk, K., Seibt, U., Vesala, T., Mammarella, I., & Chen, H. (2019). Influences of light and humidity on carbonyl sulfide-based estimates of photosynthesis. Proceedings of the National Academy of Sciences, 105, 201807600. https://doi.org/10.1073/pnas.1807600116(öffnet in neuem Fenster)
Ma, J., Kooijmans, L. M. J., Cho, A., Montzka, S. A., Glatthor, N., Worden, J. R., Kuai, L., Atlas, E. L., & Krol, M. C. (2021). Inverse modelling of carbonyl sulfide: implementation, evaluation and implications for the global budget. Atmospheric Chemistry and Physcis, 21(5), 3507–3529. https://acp.copernicus.org/articles/21/3507/2021/acp-21-3507-2021.pdf(öffnet in neuem Fenster)
Ma, J., Kooijmans, L. M. J., Glatthor, N., Montzka, S. A., Von Hobe, M., Röckmann, T., & Krol, M. C. (2023). Combined assimilation of NOAA surface and MIPAS satellite observations to constrain the global budget of carbonyl sulfide. Egusphere. https://doi.org/10.5194/egusphere-2023-1133(öffnet in neuem Fenster)
Ma, J., Remaud, M., Peylin, P., Patra, P., Niwa, Y., Rodenbeck, C., Cartwright, M., Harrison, J. J., Chipperfield, M. P., Pope, R. J., Wilson, C., Belviso, S., Montzka, S. A., Vimont, I., Moore, F., Atlas, E. L., Schwartz, E., & Krol, M. C. (2023). Intercomparison of atmospheric carbonyl sulfide (TransCom‐COS; Part Two): Evaluation of optimized fluxes using ground‐based and aircraft observations. Journal of Geophysical Research: Atmospheres. https://doi.org/10.1029/2023jd039198(öffnet in neuem Fenster)
Nagori, J., Nechita-bând, N., Danielache, S. O., & Shinkai, M. (2022). Modelling the atmospheric 34 S-sulfur budget in a column model under volcanically quiescent conditions. 1991(January), 1–30.
Parazoo, N. C., Bowman, K. W., Baier, B. C., Liu, J., Lee, M., Kuai, L., Shiga, Y., Baker, I., Whelan, M. E., Feng, S., Krol, M., Sweeney, C., Runkle, B. R., Tajfar, E., & Davis, K. J. (2021). Covariation of Airborne Biogenic Tracers (CO2, COS, and CO) Supports Stronger Than Expected Growing Season Photosynthetic Uptake in the Southeastern US. Global Biogeochemical Cycles, 35(10). https://doi.org/10.1029/2021GB006956(öffnet in neuem Fenster)
Remaud, M., Chevallier, F., Maignan, F., Belviso, S., Berchet, A., Parouffe, A., Abadie, C., Bacour, C., Lennartz, S., & Peylin, P. (2022). Plant gross primary production, plant respiration and carbonyl sulfide emissions over the globe inferred by atmospheric inverse modelling. Atmospheric Chemistry and Physics, 22(4), 2525–2552. https://doi.org/10.5194/acp-22-2525-2022(öffnet in neuem Fenster)
Remaud, M., Ma, J., Krol, M., Abadie, C., Cartwright, M. P., Patra, P., Niwa, Y., Rodenbeck, C., Belviso, S., Kooijmans, L., Lennartz, S., Maignan, F., Chevallier, F., Chipperfield, M. P., Pope, R. J., Harrison, J. J., Vimont, I., Wilson, C., & Peylin, P. (2023). Intercomparison of Atmospheric Carbonyl Sulfide (TransCom-COS; Part One): Evaluating the Impact of Transport and Emissions on Tropospheric Variability Using Ground-Based and Aircraft Data. Journal of Geophysical Research: Atmospheres, 128(6). https://doi.org/10.1029/2022JD037817(öffnet in neuem Fenster)
Vesala, T., Kohonen, K.-M. Praplan, A., Kooijmans, L., Foltýnová, L., Kolari, P., Kulmala, M., Bäck, J., Nelson, D., Yakir, D., Zahniser, M., & Mammarella, I. (2021). Long-term fluxes of carbonyl sulfide and their seasonality and interannual variability in a boreal forest. Atmospheric Chemistry and Physics, August, 1–19. https://doi.org/10.5194/acp-2021-721(öffnet in neuem Fenster)
Whelan, M. E., Lennartz, S. T., Gimeno, T. E., Wehr, R., Wohlfahrt, G., Wang, Y., Kooijmans, L. M. J., Hilton, T. W., Belviso, S., Peylin, P., Commane, R., Sun, W., Chen, H., Kuai, L., Mammarella, I., Maseyk, K., Berkelhammer, M., Li, K. F., Yakir, D., … Campbell, J. E. (2018). Reviews and syntheses: Carbonyl sulfide as a~multi-scale tracer for carbon and water cycles. Biogeosciences, 15(12), 3625–3657. https://doi.org/10.5194/bg-15-3625-2018(öffnet in neuem Fenster)
Zanchetta, A., Kooijmans, L. M. J., van Heuven, S., Scifo, A., Scheeren, H. A., Mammarella, I., Karstens, U., Ma, J., Krol, M., & Chen, H. (2023). Sources and sinks of carbonyl sulfide inferred from tower and mobile atmospheric observations in the Netherlands. Biogeosciences, 20(16), 3539–3553. https://doi.org/10.5194/BG-20-3539-2023(öffnet in neuem Fenster)