AS3.11

In Canada, offshore oil production facilities are exempt from new methane mitigation requirements that apply to onshore producers. Since onshore oil and gas operations have been shown in Canada to emit more methane than is reported in the federal inventory, it is reasonable to question methane emission levels, and intensity, of Canada’s offshore oil production. In this study, we measured methane emissions from an aircraft equipped with Picarro 2210-i gas analyzer and Aventech wind measurement system (AIMMs_30). The top-down emission rate retrieval algorithm (TERRA) was used to calculate the emission rate using a mass balance technique. The algorithm was developed by Environment and Climate Change Canada and has been used previously for airborne emissions measurement campaigns around oil and gas facilities. In addition to mass balance estimates, we also derived estimates from downwind transects using a Gaussian Dispersion model. We flew around each of the 3 offshore facilities 3 times to ensure accurate measurements considering the unpredictable offshore weather conditions. Our emissions estimates were overall comparable with inventory estimates, which demonstrate a much lower methane emissions intensity than onshore oil production in western Canada. We compared our results against reported values for other aircraft-based measurement studies including those in the North Sea and the Gulf of Mexico. Although average measured emission rates in Eastern Canada are higher in absolute terms than similar platforms in the Gulf of Mexico or the North Sea, methane emission intensity is lower because production levels are very high.

Keyword: Methane emission rate, Inventories, Mass balance, Top-down, Airborne measurement

How to cite: Khaleghi, A., MacKay, K., Bourlon, E., Lavoie, M., Darlington, A., James, L. A., and Risk, D.: Airborne emissions of methane at offshore oil platforms in Newfoundland and Labrador, Canada, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8771, https://doi.org/10.5194/egusphere-egu22-8771, 2022.

Understanding the source of fugitive methane is key to any mitigation effort. Unwanted emissions from oil and gas wells are significant contributors to greenhouse gas (GHG) emission budgets in petroliferous regions. Here we examine in detail, parameters that may be controlling GHG emission rate of individual, faulty wells in the Western Canada Sedimentary Basin (WCSB). For several hundred wells, we compared the source depth of the leaks determined by isotope fingerprinting to publicly available surface casing vent shut-in pressures and gas emission flow rates in three different oil and gas fields of WCSB. About seventy-five percent of the leaks are from shallower and intermediate formations rather than the targeted formations in most areas. The depth of leaks does not vary between horizontal and vertical wells in a given region. The source depth of the leaking gas is not correlated with the age of the well. Most of the leaks in a region come from specific gas-charged intermediate formations. We observe that smaller leaks come from both the shallower intermediate and the target zones. Surprisingly, the higher shut-in pressure and larger surface casing flows tend to come from shallower depths.  In these cases, it was observed that the drillers had used comparatively less cement. There are many thousands of faulty wells in the WCSB, and our observations can guide the prioritization of remediation to most quickly and economically reduce GHG emissions.

How to cite: Gonzalez Arismendi, G. and Muehlenbachs, K.: Insights into GHG emissions from faulty oil and gas wells in the Western Canada Sedimentary Basin, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-8989, https://doi.org/10.5194/egusphere-egu22-8989, 2022.

How to cite: Risk, D., MacKay, K., Lavoie, M., Bourlon, E., Atherton, E., O'Connell, E., Baillie, J., Fougere, C., Khaleghi, A., Coyle, L., and Vogt, J.: Methane emissions from upstream oil and gas production in Canada are underestimated, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-13337, https://doi.org/10.5194/egusphere-egu22-13337, 2022.

Anthropogenic methane emissions are generated in several economic sectors, including agriculture, waste management, oil and gas production, and others. Canada is one of the world’s largest oil and gas producers, ranks in the top-25 for agricultural production, and is the world’s largest waste producer per capita. As a result, the methane emission potential is high in parts of Canada where all these activities co-occur. To quantify emissions from multiple co-located sectors, we conducted a case study in Grande Prairie, a small city in Canada’s west dominated by oil and gas production and agriculture. Our goal in this study was to produce a gridded dataset of emissions for the Grande Prairie region. In November 2021, we measured atmospheric mixing ratios of methane using a high-precision gas analyzer mounted in a truck, and estimated emission rates using an inverse Gaussian plume model. During our campaigns, we passed downwind of roughly 220 oil and gas sites and 20 farms with grazing cattle or bison present. We detected emissions at about one-quarter of the oil and gas sites and one-third of the farms, and we also observed emissions from waste management and power generation facilities. Methane emissions from oil and gas production sites were relatively low compared to others we have measured in Canada, but despite this we still found that oil and gas was the dominant methane-emitting sector in the Grande Prairie region. The results of this study feed into a long-term methane monitoring study, focused on multiple economic sectors, methane source types, and detection approaches.

How to cite: Vogt, J., Perrine, G., Bourlon, E., Lavoie, M., and Risk, D.: Quantification of methane emissions from anthropogenic sources: A case study in Canada, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6532, https://doi.org/10.5194/egusphere-egu22-6532, 2022.

In the summer of 2020, the AVIRIS-NG airborne imaging spectrometer surveyed California’s Southern San Joaquin Valley and the South Bay (Los Angeles County) to identify anthropogenic methane point source plumes, estimate emission rates, and attribute sources to both facilities and emission sectors. These flights were designed to revisit regions previously surveyed by the 2016-2017 California Methane Survey (Duren et al., 2019) and to assess the impact of COVID-19 on emissions across multiple sectors. For the region flown by both the California Methane Survey (summer, fall 2016-2017) and the California COVID campaigns (summer, fall 2020), total emissions from point sources from the IPCC sectors for Energy Industries and Oil & Natural Gas were 34% lower during the 2020 flights. However, emission trends varied across different sectors. For the Energy Industries sector, there was a 19% decrease driven by reductions in refinery emissions consistent with a drop in production during 2020, which was offset in part with increases from powerplants. For the Oil & Natural Gas sector, emissions declined 35% and significant variability was observed at the oilfield scale. Emissions declined for all but the Buena Vista and Cymric oilfields with an observed relationship between production and emissions. These results indicate that imaging spectrometer surveys can characterize changes in anthropogenic emission profiles over time, including those associated with disruptive events like COVID-19.

How to cite: Thorpe, A., Kort, E., Duren, R., Cusworth, D., Herner, J., Falk, M., Bue, B., Yadav, V., Thompson, D., Green, R., Miller, C., and Frankenberg, C.: COVID-19 impacts on California methane point source emissions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10510, https://doi.org/10.5194/egusphere-egu22-10510, 2022.

Methane (CH₄) is the second most important anthropogenic greenhouse gas (GHG) in terms of its overall effect on climate radiative forcing. The atmospheric residence time of methane is considerably shorter than that of carbon dioxide, but its warming potential significantly stronger. Methane is produced from natural sources such as wetlands, and as a result of human activities, such as the oil and gas industry. A small number of anomalously large anthropogenic point sources are a major contribution to the total global anthropogenic methane emission budget, thus early detection of such sources has great potential for climate mitigation.

Methane satellite observations are now possible from a number of instruments with very high spatial resolution which allow to map methane emission plumes from individual emission sources.  In this work, we explore the capabilities of three satellites with different specifications, spatial coverage and spatial resolutions ranging from metres (WorldView-3; multi-spectral) to tens of metres (PRISMA; hyperspectral) to kilometres (TROPOMI; hyperspectral). This leads to different capabilities for detecting and quantifying methane point sources that can complement each other.  Thanks to its good coverage, TROPOMI Level 2 XCH4 data (from IUP Bremen) allows to locate areas with methane anomalies which can then be further analysed with targeted PRISMA and WorldView-3 (WV-3) observations to quantify methane emissions from small point sources.

In our work, we use a fast data-driven retrieval algorithm to derive methane column enhancements from PRISMA and Worldview-3, combined with a statistical method to identify methane plumes and the well-established Integrated Mass Enhancement (IME) method to derive emission flux rates. We developed a simulation framework to characterise and test our approach. This makes use of synthetic methane plumes generated with the Large Eddy Simulation extension of the Weather Research and Forecasting model (WRF-LES) that have been embedded into WV-3 or PRISMA images. To further advance the plume detection methods and to allow automatisation, we have developed a deep learning model for WV-3 or PRISMA based on the WRF-LES simulations.

In this presentation, we will describe and characterise our plume detection method for three satellite systems covering a wide range of spatial resolutions and we will introduce our deep learning approach. Both methods have been applied to case studies with a focus on emissions from coal mining in South Africa and Australia which we will use to discuss and contrast the different methods and satellite systems.

How to cite: Ruiz Villena, C., Boesch, H., Parker, R., Webb, A., Barrio Guilló, R., Sembhi, H., Joyce, P., Huang, Y., Chipperfield, M., Gloor, E., Wilson, C., Palmer, P., and Lunt, M.: Methane point source detection and quantification from high-resolution satellite observations and deep learning methods, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11695, https://doi.org/10.5194/egusphere-egu22-11695, 2022.

Methane (CH4) is one of the most contributing anthropogenic greenhouse gases (GHGs) in terms of global warming. Since some years, satellites based CH4 product show ability to monitor large-scale variabilities and trends. In the same time, several works have proven the feasibility of quantifying anthropogenic methane plume at metric resolution using airborne hyperspectral imagers 
[Frankenberg et al. 2016]. More recently, the launch of high spatial resolution (decametric) satellites such as PRISMA has already demonstrated the feasibility of providing methane map of anthropic plumes [Guanter et al. 2021]. This paper focuses on methodological improvement of gas plume segmentation and quantification from satellite hyperspectral data at high spatial resolution and applications to PRISMA data over Turkmenistan oil and gas site during two years (2020-2021) [Nesme et al. 2021]. 

First, the ISBR-OE method based on in-scene background radiance (ISBR) estimation and an Optimal Estimation (OE) approach is presented. One principle of the method is to estimate the background radiance by spatial and spectral search in the “free-methane” part of the image. It is useful to avoid radiative transfer model time-consuming calculations for atmospheric retrieval in particular in the OE quantification step. Flow rates of methane-emitting sources were quantified for different dates by using the images one by one in an independent way (mono-temporal approach). 

In this paper, we focus on the plume segmentation: identification of the pixels affected by an industrial source. The ACE probability score, commonly used in image processing, is applied to compare the theoretical signature of the methane with the observed signature class by class. In the first instance, we worked on a single image. In mono-temporal case, this score leads to the plume but also to many false alarms when a single threshold is applied. For this reason, we developed an isolation method based on thresholding, morphological transformations, labelling and spatial study of regions. This helps to remove most of the false alarms and artefacts in the detection map caused in particular by roads, buildings or clay. 

In the second instance, this paper introduces a multi-temporal (multi-T) approach. One of the advantages of satellite data is the revisit time period which is not always possible with airborne campaigns. This approach is based on the joint use of data from different dates. It is assumed that the reflectance varies slowly between two passes, unlike the atmosphere. A mean atmospheric 
correction is therefore applied to each image. The ACE score applied on the difference of the two images, increases the plumes contrast on the two images (with positive and negative scores). The use of a multi-T approach improves the quality of the detection map and decreases the false alarms rate: roads and buildings are no longer detected as pixels with a methane signature. So, the complex image processing used for the mono-temporal segmentation can be replaced by a simple thresholding in multi-T approach. Nevertheless, the use of multi-temporal approach for the quantification step requires high accuracy in the atmospheric correction process and to deal with natural reflectance temporal and directional variations.

How to cite: Nesme, N., Foucher, P.-Y., and Doz, S.: Mono and multi temporal approaches for detecting and quantifying industrial methane plumes using PRISMA hyperspectral satellite data, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-3360, https://doi.org/10.5194/egusphere-egu22-3360, 2022.

Methane emissions from industrial activities represent a significant fraction of total greenhouse gas emissions. It is vital to provide industrial site operators with accurate and timely information about their emissions -- GHGSat’s constellation was built for this purpose. Each of the constellation satellites can do multiple measurements of 150 km2 domains each day with a pixel resolution of 25 meters allowing to detect, quantify and attribute emissions to a given facility. With 3 satellites currently in operation, this allows multiple measurements of a site in a year and help operators minimize their emissions.

We will present the performance of our instruments showing a column precision of 1% of background and a detection threshold of 100 kg/h for point sources. Examples from a variety of anthropogenic sources will illustrate the system capability.  A statistical analysis of all detected emissions will serve to evaluate the distribution of global source rates, source intermittency and breakdowns by region and by sector. An estimate of emissions mitigated thanks to GHGSat’s constellation will also be presented. Finally, the schedule of the next phases of the constellation will be outlined.

How to cite: Strupler, M., Jervis, D., MacLean, J.-P., Marshall, D., McKeever, J., Ramier, A., Tarrant, E., and Young, D.: Assessment of GHGSat’s constellation one year after its first phase deployment, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6173, https://doi.org/10.5194/egusphere-egu22-6173, 2022.

Greenhouse gases like CO₂ and CH₄ play an important role in the earth’s energy budget. Both local sources and long range transport can influence their concentration in the atmosphere. Within the Ruisdael project, which aims to map and understand the atmosphere over the Netherlands in a changing climate, a trailer was fitted with a range of instruments for flexible operations within the Ruisdael Observatory measurement network, among them an EM27/SUN, on which we will focus here. This instrument is a portable Fourier transformation infrared spectrometer to measure the columnar abundance of the trace gases CO₂, CH₄ and CO from the spectral absorption of direct sun light. The additional CO measurements can provide valuable information for attributing CO₂ and CH₄ enhancements to either biological processes or fuel burning. The instrument was equipped with a custom build rain cover that is fixed to the moving sun tracker and set up for remote operation, which greatly increased data coverage. It was then installed on the roof of the Ruisdael trailer, along with several in situ instruments inside.

The EM27 was deployed in the Ruisdael trailer at the Cabauw tall tower site from May till September 2021. The RITA (Ruisdael Land-Atmosphere Interactions Intensive Trace-gas and Aerosol measurement campaign) campaign took place in and around the Cabauw tower in September 2021. During this time, additional measurements in the boundary layer by a mobile truck and an aircraft give the possibility of separating local and regional influences on the columnar trace gas abundance. Here, we present the results from the columnar trace gas measurements in the context of the large scale circulation and the in-situ measurements at the tower, with the mobile truck, and by aircraft. While the in situ measurements capture local pollution very well, only the larger pollution plumes are distinguishable in the EM27 data. The CO₂ columnar abundance is mostly influenced by the large scale circulation. In the columnar abundance of CH₄ and CO, larger pollution plumes are distinguishable as increases of up to several ppb. The presented measurements demonstrate how the EM27 can help to distinguish influences of local emissions and large scale transport in an urban monitoring network.

How to cite: Heimerl, K., Houweling, S., Eeuwijk, L., van der Plas, W., Limburg, R. J., Hensen, A., van den Bulk, P., and Scheeren, B.: Remote sensing of trace gases as link between small and large scale pollution sources in the Ruisdael Observatory, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5752, https://doi.org/10.5194/egusphere-egu22-5752, 2022.

Methane (CH₄) is a greenhouse gas emitted from natural emissions that pre-dominantly come from wetland sources, and from a wide range of anthropogenic sources including livestock, oil–gas systems, landfills, coalmines, wastewater management, and rice cultivation. Since the global warming potential of CH₄ far outweighs that of carbon dioxide (CO₂), this means that policies aimed at reducing CH₄ emissions are key to combating climate change on shorter timescales. Significant gains can be achieved by avoiding accidental or uncontrolled CH₄ emissions from industrial or waste-treatment sites and methods for active monitoring of such sites will play an important role to support this.

For many localised emitters such as landfill sites, it is often difficult to ascertain the level of compliance and effectiveness of waste management protocols used by local authorities, particularly in emerging and developing countries. Some landfill sites are so poorly regulated that there is little handle on the scale and intensity of CH₄ emissions and pollution originating from these sites. Furthermore, in uncontrolled landfill sites, waste can spontaneously combust and lead to the emission of flammable CH₄ gas from decomposition of biological material further aggravating pollution in densely populated cities. For example, in the case of Indian megacities such as Delhi, some landfill sites exceeded their full capacity well over a decade ago and authorities are making important efforts to implement alternative measures to manage and reduce the waste in these landfill sites.

Satellite sensors can map CH₄ emission plumes from strong point sources that can be undetected by sparse ground-based networks and they provide us with a powerful new tool to characterize and quantify the rate and intensity of landfill CH₄ emissions. The recently launched satellite missions such as the Sentinel 5p (carrying onboard the TROPOMI spectrometer) offers the potential to observe such CH₄ plumes on a global scale but with relatively coarse spatial resolution (7km). This is complemented by high-resolution sensors such as the GHGSat imager that offer much improved pixel sizes (tens of m) that can map CH₄ sources at a much finer scale but with very limited coverage.

Here we present an evaluation of landfill CH₄ emission rates for landfill sites located across Indian megacities using a combination of TROPOMI and space-borne imager observations. We will show an analysis of CH₄ observations over India using the University of Bremen TROPOMI/WFMD CH4 product to identify CH₄ enhancements across Indian landfill sites. We focus on the Ghazipur landfill site in the megacity of Delhi as well as sites in Mumbai and West Bengal and use the cross-sectional flux method to determine the largescale CH₄ emissions originating from these sites. We will discuss the challenges in estimating CH₄ source rates from point sources and present the approach used to detect and quantify CH₄ from Indian landfills from TROPOMI. We will present an evaluation of our estimates against in-country Indian municipal solid waste emission inventories as verification and demonstrate the value of satellite observations in supporting authorities implement corrective actions to better manage landfill emissions.

How to cite: Sembhi, H., Boesch, H., Ruiz Villena, C., Barrio Guillo, R., Trent, T., Kumar Kunchula, R., Dey, S., Pal, S., and Schneising, O.: Estimating landfill methane emissions in Indian megacities with Sentinel 5p TROPOMI, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11788, https://doi.org/10.5194/egusphere-egu22-11788, 2022.

Estimating the contribution of cities and urban areas to the regional and global methane budget is challenging due to their complex infrastructure. The use of mobile measurement devices provides a well-suited way to detect methane sources via real-time ambient air measurements. Surveys with mobile CH₄ measurements were conducted from May 2020 to January 2021 in the city area of Heidelberg. This made it possible to cover a third of Heidelbergs entire road network via real-time ambient air measurements. Leak indications for methane were observed and recorded with an excess of 100 to 4600 ppb CH₄ above the background concentration. A minor portion of leaks was attributed to the sewer system while most of them originate from natural gas leaks in the urban gas distribution system with 2.1 covered km per leak indication.

To assign an emission rate to all of the leak indications a method, developed by Weller et al. (2019)² based on release experiments and mobile measurements, was used and adapted to Heidelberg. We tested this method with additional CH₄ release experiments and modified it to the smaller street widths in Heidelberg resulting in shorter distances from the source to the measurement device. The total annual CH₄ emission rate calculated for Heidelberg, up-scaled to the entire road network, is 42 tCH₄ yr^-1. This results in an emission rate of 0.26 kgCH₄ yr^-1 per capita.

²Weller, Z. D., Yang, D. K., & von Fischer, J. C. (2019). An open source algorithm to detect natural gas leaks from mobile methane survey data. Plos One, 14(2), e0212287. doi:10.1371/journal.pone.0212287

How to cite: Wietzel, J. and Schmidt, M.: Mapping Street Level CH4 Emissions in the Urban Area of Heidelberg (Southwest Germany), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-9613, https://doi.org/10.5194/egusphere-egu22-9613, 2022.

Methane (CH₄) is the second most important greenhouse gas. However, the measurement of urban CH₄ flux is exceptionally scarce. Here we present the observational results based on the eddy-covariance method at the high-rise and high-population residential area in Seoul, Korea. The magnitude and temporal variation of CH₄ flux show a significant strong relationship with carbon dioxide emission rate. The observed emission rate of CH₄ over the residential area is 21.8 nmol m^-2 s^-1 on average, and this is corresponding to 11 gC m^-2 yr^-1 which is comparable with boreal, taiga, and temperate wetlands. The carbon-isotope compositions (δ¹³C) of CH₄ (about -46‰) and CO₂ (about -28‰) point to the same source for both gases suggesting vehicular traffic as a dominant source for CH₄ in this study. 

This study is supported by “National Adaptation Plan for Climate Change” (2022-001-01), conducted by the Korea Environment Institute (KEI) upon the request of the Korea Ministry of Environment, and the Korea Meteorological Administration Research and Development Program (grant no. KMI2021-01610).

How to cite: Lee, K., Hong, J.-W., and Hong, J.: Methane flux and its relationship with carbon dioxide emission in urban residential areas in Seoul, Korea., EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6785, https://doi.org/10.5194/egusphere-egu22-6785, 2022.

Methane is considered as the second most important contributor to radiative forcing and thus makes it the most important non-CO₂ greenhouse gas originated from anthropogenic activities. The investigation of emission sources and the mitigation strategies of these is of major importance. One of several approaches quantifying methane emissions is the top-down eddy covariance flux measurement, which is used in the investigation here.

Long-term eddy covariance flux measurements of methane over urban areas can be used to constrain important urban emission sources. These include traffic, the residential, commercial and public sectors, industry, and biogenic sources. It is believed that a large fraction of methane emissions originates from fugitive emissions, but the magnitude and nature are still poorly constrained. Here we present initial results from long-term measurements at an Alpine city (Innsbruck, Austria), and compare methane fluxes with those available from other locations. We show that a statistical gap filling model allows to compare yearly top-down methane fluxes with bottom-up emission models. The temporal and spatial disaggregation of eddy covariance flux data can be used further to hunt down and identify potential urban emission sources, by combining these fluxes with additional tracer fluxes (e.g. NMVOC, NOx, CO₂). An analysis of the methane fluxes referring to heating degree days and weekday/weekend effect combined with similar analysis for trace gases like NOx, provides additional clarity about the origin of the methane emissions (e.g. traffic, residential combustion).

First results from the methane flux measurements performed during the years 2020, 2021 and 2022 are presented here.

How to cite: Stichaner, M., Karl, T., Graus, M., Lamprecht, C., Goded, I., and Jensen, N.: Eddy covariance flux measurements of methane over an urban area in the Alps, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-5396, https://doi.org/10.5194/egusphere-egu22-5396, 2022.

Decreasing trends of Arctic Seas ice areas, recorded growth of sea surface temperatures, and the increasing influx of Atlantic water into the Arctic Ocean demonstrate progressing warming. According to the current knowledge, the Kara Sea is characterized by a presence of subsea permafrost only in the nearshore area west of the Yamal peninsula. Limited summertime data on dissolved methane (CH₄) dynamics indicate its low-moderate values in the shallow zone. In contrast to the deep subsea locations where CH₄ is mostly oxidized in the water column, an essential part of CH₄ that is released at the seafloor in the shallow Kara Sea emits into the atmosphere. Hence, accurate stationery and mobile observations of atmospheric methane over the above-sea layer might capture a portion of CH₄ signals that are related to specific patches of such emissions. This study was accomplished during/after fall convection which fully mixed the shallow water column characterized by the near background concentration of dissolved CH₄. Then to explain the “empty” dissolved CH₄ pool we suggested effective extraction of dissolved methane into the atmosphere during fall water mixing. Such a “dissolved methane ventilation phenomenon” caused by wind-driven mixing has been discovered in the shallow part of the Laptev Sea.

Accurate continuous observations of atmospheric CH₄ dry mole fractions and δ13C-CH₄ were made during the beginning of the freeze-up period - on October, 02 – November, 05 2021 onboard the research vessel "Academician Mstislav Keldysh" (AMK-86). Atmospheric measurements at 15 m of the above-sea layer were performed by a CRDS analyzer Picarro G2201-I (Picarro Inc., USA) that passed a regular calibration against WMO-traceable reference gases. Associated meteorological and geospatial records permitted screening and interpreting trace gas data series. Additionally, analysis of specific source regions of atmospheric air parcels moving downwind to the research vessel was based on the ARL NOAA HYSPLIT model.

Here we give an overview of CH₄ and δ13C-CH₄ fluctuations over the above-sea layer of the Kara Sea observed within longitudinal (60 – 84^о E) and latitudinal (70 – 82^о N) transects, summarize spatial features, and provide analysis of source regions contributed into the accurate continuous measurements. This study was funded by the Russian Foundation for Basic Research, Krasnoyarsk Territory, and Krasnoyarsk Regional Fund of Science, project number 20-45-242908, Russian Science Foundation (RSF) project 21-17-00163, and by the Max Planck Society (Germany). Fieldwork was funded by the RSF project 21-77-30001. IS and DK acknowledge the Ministry of Science and High Education (grant ID: 075-15-2020-928).

How to cite: Panov, A., Prokushkin, A., Evgrafova, S., Tsukanov, A., Korets, M., Kosmach, D., Saluk, A., Seifert, T., Heimann, M., Gustafsson, O., and Semiletov, I.: Research vessel-based accurate continuous observations of CH4 and δ13C-CH4 in the above-sea atmosphere of the Kara Sea (Arctic Ocean), EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11681, https://doi.org/10.5194/egusphere-egu22-11681, 2022.

The Upper Silesian Coal Basin (USCB), with its coal mines ventilating methane (CH4), is among the
largest localized CH4 sources in Europe. The reported emission rates, however, vary broadly among
the emission inventories ranging between 405 ktCH4 (GESAPU, for the year 2010) and 720 kt (EDGAR
v4.3.2, for the year 2017). Thus, independent verification is required to constrain the actual
emissions better.
Here, we report on a demonstration study conducted in May/June 2018 in the framework of the
CoMet campaign in the USCB. During the campaign, five direct-sun spectrometers of the COCCON-
type (Carbon Column Observing Network) were deployed in the region measuring column
concentrations of CH4. One of the spectrometers was operated on a van sampling plumes of
individual ventilation facilities [Luther et al., 2019]; the other four spectrometers were operated in a
stationary network at a distance of roughly 50 km enclosing the USCB [Luther et al., 2021]. In
addition, we ran three wind-lidars in the region to constrain atmospheric transport. The
spectrometers detected downwind enhancements of CH4 concentrations unambiguously
attributable to coal mine ventilation. For the mobile spectrometer, we used a mass balance method
to infer emission rates for individual facilities. For the network, we used pairwise upwind-downwind
concentration gradients together with air mass trajectory modelling by WRF/FLEXPART to estimate
emission rates for groups of facilities. The Tikhonov-based inverse method delivered the diagnostics
for quantifying the information content attributable to the facilities. We show that our approach
allows estimating emissions rates with uncertainties of 20-35% largely dominated by uncertainties in
atmospheric transport. This stresses the importance of wind measurements together with the CH4
observations. Overall, scaling our hourly-to-daily emission estimates to a year indicates that they are
greater or equal to the ones reported by EPRTR (European Pollutant Release and Transfer Register).

Luther, A., Kostinek, J., Kleinschek, R., Defratyka, S., Stanisavljevic, M., Forstmaier, A., Dandocsi, A.,
Scheidweiler, L., Dubravica, D., Wildmann, N., Hase, F., Frey, M. M., Chen, J., Dietrich, F., Necki, J.,
Swolkien, J., Knote, C., Vardag, S. N., Roiger, A., and Butz, A.: Observational constraints on methane
emissions from Polish coal mines using a ground-based remote sensing network, Atmos. Chem. Phys.
Discuss. [preprint], https://doi.org/10.5194/acp-2021-978, in review, 2021.

Luther, A., Kleinschek, R., Scheidweiler, L., Defratyka, S., Stanisavljevic, M., Forstmaier, A., Dandocsi,
A., Wolff, S., Dubravica, D., Wildmann, N., Kostinek, J., Jöckel, P., Nickl, A.-L., Klausner, T., Hase, F.,
Frey, M., Chen, J., Dietrich, F., Nȩcki, J., Swolkień, J., Fix, A., Roiger, A., and Butz, A.: Quantifying CH 4
emissions from hard coal mines using mobile sun-viewing Fourier transform spectrometry, Atmos.
Meas. Tech., 12, 5217–5230, https://doi.org/10.5194/amt-12-5217-2019, 2019.

How to cite: Luther, A., Kostinek, J., Kleinschek, R., Defratyka, S., Stanisavljevic, M., Forstmaier, A., Dandocsi, A., Scheidweiler, L., Dubravica, D., Wildmann, N., Hase, F., Frey, M. M., Chen, J., Dietrich, F., Necki, J., Swolkien, J., Knote, C., Vardag, S. N., Roiger, A., and Butz, A.: Quantifying CH4 emissions from coal-mine ventilation in the Upper Silesian Coal Basin (Poland) using COCCON spectrometers, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-6488, https://doi.org/10.5194/egusphere-egu22-6488, 2022.