Methane is a powerful greenhouse gas with a globally averaged atmospheric mole fraction of 1908±2 ppb in 2021, nearly three times the pre-industrial abundance. The annual increase of methane between 2020 and 2021 was the highest since continuous measurement began (WMO,2022).  More than 60% of global CH₄ emissions are attributed to human activities. Reducing methane in the short term will help to achieve the Paris Agreement goal to keep warming to <1.5°C and help in reaching many Sustainable Development Goals due to multiple co-benefits of methane mitigation. The fossil fuel sector is one of the largest anthropogenic emitters of methane and a target for CH₄ reductions, with the UN stating that an emissions reduction of 61% is possible, but there is now urgent need to implement this (Nisbet et al, 2019).

Sources of fugitive methane emissions in the UK have been identified and characterized by mobile measurement survey in vehicles (e.g. Lowry et al ,2020) and aircraft (e.g. France et al., 2021). Since 2017, vehicles surveys for UN and NERC-UK projects have identified emissions from production platforms, onshore terminals, compressor stations, offtake stations, gas governors and pipeline failures.

Vehicle surveys utilized different suites of instruments: Picarro G2301 and G2210-i Los Gatos Research Ultraportable Methane-Ethane (LGR UMEA), and LiCor 7810 GHG analyzers, all measuring methane. Air bags were filled in plumes during surveys to measure the carbon isotopic signature (δ¹³C) at different points in the gas distribution supply chain. The range of signatures identified is from -43.7 to -32.4 ‰ (n=182), showing an enrichment relative to atmospheric background (-48 to -47.5‰), with the southern North Sea production that feeds into the Bacton Terminal identified as the most enriched at -31.8 ±1.5‰ (n=13).

Ethane:methane ratio is a useful diagnostic for gas attribution. Since 2018 the LGR UMEA ethane data has been used to identify distribution leaks as this gas is not a component of waste, agricultural or coal sources. The ratio of C₂H₆:CH₄ (C2:C1) during surveys of gas allows separation of pyrogenic and thermogenic (>0.03) from biogenic (<0.005) sources (Rella et al, 2015: Lowry et al, 2020), with UK gas distribution dominantly in the range 0.04 to 0.08, and it is consistent for fugitive plumes transected on multiple passes.

Most of the larger peaks have been located downwind of offtake stations on the high-pressure mains network. The 2021 surveys focused on identification of emitting facilities and their isotopic and C2:C1 characterization. Recent surveys in 2022 targeted emission plumes for multiple passes with 10Hz and 1Hz instruments to select suitable candidates for Gaussian plume emission modelling, with potential to upscale to a national emission for facilities of this category.

France et al., 2021, Atmos. Meas. Tech., 14, 71–88, 10.5194/amt-14-71-2021

Lowry et al., 2020, Science of the Total Environ., 708, 134600, 10.1016/j.scitotenv.2019.134600

Nisbet et al., 2019., Global Biogeochem. Cycles, 33, 25pp, 10.1029/2018GB006009 

Rella et al., 2015., Atmos. Meas. Tech., 8, 4539–4559, 10.5194/amt-8-4539-2015.

World Meteorological Organisation, 2022. (WMO) greenhouse gas bulletin. [Online]. Available at: https://public.wmo.int/en/resources/library/wmo-greenhouse-gas-bulletin. (Accessed 9 December 2022)

How to cite: Al-Shalan, A., Lowry, D., Fisher, R., France, J., Fernandez, J., and Lanoiselle, M.: Fugitive Methane Detection from UK Above Ground Gas Infrastructure, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-1141, https://doi.org/10.5194/egusphere-egu23-1141, 2023.

In this study, we examine a maximum of 13 years (2009-2021) of the observational datasets of columnar dry-air mole fractions of methane (XCH₄), from the Greenhouse gases Observation SATellite (GOSAT) GOSAT-1 (2009-2021) on board the IBUKI satellite and vertical profiles of CH₄ from the Atmospheric Infrared Sounder (AIRS) on board AQUA satellite. We also use the XCH₄ and vertical distributions over the Indian subcontinent from the JAMSTEC’s MIROC4 atmospheric chemistry transport model (ACTM) from 2009-2021, after convolution with GOSAT-1 and AIRS a priori profiles and averaging kernels. 

A comparison of observed and modeled CH₄ and XCH₄ reveals that MIROC4-ACTM provides explicit insights into the spatio-temporal variability of atmospheric methane over the Indian region. Global CH₄  emission inventory EDGARv7.0 reports a total of ~30 Mt of anthropogenic emissions in India in 2020 while GAINS emissions stand at ~33Mt for the same year. The ACTM simulations from this study are also examined to retrieve preliminary information on the quality of these constructed bottom-up fluxes of methane (EDGAR and GAINS).      

Our time series analysis of GOSAT-1 shows the annual mean XCH₄ has increased by 100 ppb from 2009 to 2021 over the Indian subcontinent, compared to 85 ppb globally in the latitude band of 6.25 °N-41.25 °N. Observations from both AIRS and GOSAT-1 show distinct seasonality in the vertical profiles of CH₄ and XCH₄ over the entire region, respectively. Seasonality in the CH₄  concentration over India in boundary layer heights (>850 hPa) is affected majorly by the local emission strengths while in the middle (400- 600 hPa) and upper (< 200 hPa) troposphere it is governed by the convective transport of surface emissions signals and redistribution in the monsoon winds in the upper troposphere. GOSAT-1 shows highest XCH₄ of ~1900 ppb (2021) in northern India (North of 20° N) in winter season  (November) while AIRS shows highest CH4 ~1910 ppb in summer month of May at 200 hPa for the same year. Based on the findings from the vertical (AIRS) and total column (GOSAT-1) distribution of CH₄, our analysis suggests that 3D variability of CH₄ over the entire Indian region is governed by a diverse spread of surface emissions and global monsoon divergent wind circulations.  

Through this study, the reasons for these observed patterns of CH₄ are explored in light of forward model results using an ACTM by combining and comparing the strengths of AIRS and GOSAT-1.

How to cite: shikha, D., Dey, S., and K. Patra, P.: A view of 3D variability of atmospheric methane over India using  MIROC4-ACTM simulations, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-2237, https://doi.org/10.5194/egusphere-egu23-2237, 2023.

As global warming continues to be one of the greatest threats to Earth environment, the detection and monitoring of natural and anthropogenic emissions of greenhouse gases holds a critical role as the first step of any danger reduction policy. New generation spaceborne hyperspectral instruments cover large portions of the Earth while maintaining a high enough spectral and spatial resolution to investigate the contribution of single molecular species and accurately localize their emission source. The Matched Filter method is used to search enhanced concentrations of methane in the atmospheric column. PRISMA, ASI’s newest hyperspectral sensor, data are analysed. Both strong and weak CH₄ emissions, in multiple scenarios, are investigated. It is demonstrated that PRISMA data allow also the identification of methane non-punctual sources when the land gas emission is very high. An estimated flux in the order of 4000 kg/h is found for a case study considering a landfill in India.

How to cite: Masin, F., Maestri, T., and Martinazzo, M.: About the use of Satellite Hyperspectral Images for Methane Detection, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6606, https://doi.org/10.5194/egusphere-egu23-6606, 2023.

In the worldwide effort to reach the 1.5-degree target, governments try to mitigate anthropogenic methane emissions. One example is the oil & gas sector, which is responsible for the second most anthropogenic methane emission source after agriculture. Abandoned oil and gas wells are seen as a promising target, as they can in some cases emit up to several tons of methane per year. However, only the USA includes emissions from such wells into their yearly greenhouse gas emission inventory and only for a few other countries like Canada, the United Kingdom, Romania and the Netherlands measured data on methane emissions from abandoned gas wells are available. Most countries do not even have sufficient data regarding numbers, positions, and status of their abandoned wells let alone the related methane emissions. Germany has about 20,000 abandoned wells, which are generally filled and buried, however, it is unclear, whether they are emitting methane or not.

Here, we present our approach and first data to fill this knowledge gap for Germany regarding methane emissions from onshore-abandoned oil and gas wells. For our first measuring campaign we focused on five regions in Lower Saxony (Federal State in Northern Germany) measuring 29 wells, covering both backfilled exploration and abandoned production wells of oil and gas fields. We will present our preliminary results including rates of soil methanotrophy focusing on one region with both, shallow oil wells and industrial peat production. Our data demonstrate the necessity for detailed knowledge on background methane emissions and cycling particularly in such methane-laden settings.

How to cite: Jordan, S., Schlömer, S., Krüger, M., and Blumenberg, M.: Methane cycling at buried abandoned wells in a peat-rich area in northern Germany – curse or blessing for atmospheric emissions and emission studies?, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-6837, https://doi.org/10.5194/egusphere-egu23-6837, 2023.

A field campaign using UAV-based measurements to derive methane fluxes from a large landfill site in North Manchester was conducted in the summer of 2022. The system comprises the newly developed ABB lightweight (3kg) Hoverguard greenhouse gas analyser based on the off-Axis Integrated Cavity Output Spectroscopy (with a precision of 0.9 ppb for CH4 at 1 Hz), an on-board TriSonica™ Mini wind sensor and the DJI M600 pro hexacopter.  Fluxes and corresponding flux uncertainties were calculated using the mass-balance method from 6 flight surveys conducted downwind of the active landfill. Accurate and reliable wind measurements sampled from instrumentation onboard rotary-wing UAVs remains a challenge, which was found to dominate flux uncertainty in this study. This study presents a low-cost and repeatable methodology for hotspot methane emission quantification.

How to cite: Yong, H., Allen, G., and Ricketts, H.: UAV-based methane emission quantification at a UK landfill site, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7229, https://doi.org/10.5194/egusphere-egu23-7229, 2023.

There is consensus that climate change is mostly driven by anthropogenic greenhouse gas emissions. In addition to CO₂ emissions, which have been the subject of public debate for a long time, increased awareness of methane (CH₄) emissions has developed in recent years. CH₄ is considered the 2^nd most important contributor to radiative forcing, making it the most important non-CO₂ greenhouse gas.

Due to the relatively short lifetime of the gas in the  atmosphere compared to CO₂, the reduction of methane emissions can lead to a climate benefit on relatively short time horizons. In order to effectively reduce emissions, the polluters must be better understood and recognized. Here, we combine methane eddy covariance observations in combination with a variety of other trace gases and meteorological parameters that have been recorded since August 2020 in an Alpine city (Innsbruck, Austria) to investigate urban methane emissions. For an accurate comparison with bottom-up emission inventories we test different gap-filling methods with the help of meteorological parameters as well as other tracer fluxes, such as NO, NO₂, or CO₂. In order to quantify methane emissions in urban areas as annual totals, a complete, gap-free flux dataset is desired. We have developed different statistical gap filling models which are able to predict CH₄ fluxes at the study location. The method is based on a boosted regression tree model with a variety of meteorological and astronomical parameters, as well as other trace gas fluxes serving as input. Different combinations of these input parameters are tested for accuracy of their prediction. Contrasting other gap filling methods, used over uninhabited areas, adding gases like CO₂ or NO can serve as important additional predictors, because sectors related to combustion processes are considered as important contributors to CH₄ emissions.  In this presentation we discuss CH₄ flux measurements performed during the last 2,5 years over an urban area, and highlight first results on the performance of the developed gap filling models. 

How to cite: Stichaner, M., Lamprecht, C., Graus, M., Goded, I., Jensen, N., and Karl, T.: A statistical gap filling model for methane fluxes over an urban area in the Alps, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7706, https://doi.org/10.5194/egusphere-egu23-7706, 2023.

Sewer systems, which consist of wastewater treatment plants (WWTPs) and sewer networks, are important urban water infrastructure that helps to improve water quality and prevent flooding. While they are recognized as a major source of methane emissions with considerable potential, accurate quantification of methane emissions from sewage systems has not yet been achieved. Here, we measured atmospheric methane from the urban sewer network using a mobile laboratory, which consists of the electric vehicle and monitoring instruments for Greenhouse Gas (GHG) such as carbon dioxide (CO2), methane (CH4), and ethane (C2H6). The mobile measurements of sewer networks are conducted in Gwanak district of Seoul in South Korea from September 2022. More than 3,000 manholes and rain gutters in commercial and residential areas were measured for the methane emissions of the combined sewer network type in Gwanak district. The methane emissions from urban sewer network were found to be significant in the study area. However, these emissions are currently not included in the national GHG inventory. Further details of our findings will be introduced at the European Geosciences Union (EGU) General Assembly 23.   

This work was supported by Brain Pool Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science and ICT (No.2019H1D3A1A01101988)

How to cite: Joo, J., Jeong, S., Shin, J., and Chang, D. Y.: Quantification of methane emissions from urban sewer network, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11170, https://doi.org/10.5194/egusphere-egu23-11170, 2023.

Methane (CH4) is after carbon dioxide the second most important anthropogenic greenhouse gas. Due to its comparatively short lifetime of ~10 years, a significant reduction in anthropogenic CH4 emissions would help to reduce the atmospheric concentration within a decade with near term temperature benefits. However, the development of efficient mitigation strategies needs to be informed by identifying, locating and quantifying CH4 emissions from the different sectors. A large part of CH4 emissions from the global oil and gas sector is expected to arise from offshore production, which currently however is understudied. Off the coast of Gabon and Angola, oil and gas production is spread over more than 800 kilometres across a wide variety of offshore installations, covering both shallow waters and deep sea. Here we report on airborne measurements conducted using the DLR Falcon along the west coast of Central Africa in September 2022. The DLR Falcon was equipped with a suite of different in-situ instruments to measure CH4 and a series of other trace species, as well as meteorological variables. Measurements were taken during 15 science flights to quantify emissions related to offshore oil production. We will present and discuss our airborne results on regional and facility-scales, in dependency of e.g. infrastructure type and age, and compare them with available inventory estimates and industry reportings. Our collected data, co-funded by the International Methane Emissions Observatory (IMEO), will help coal, oil and gas companies and governments, to prioritize their methane emission mitigation .

How to cite: Roiger, A., Eckl, M., Puehl, M., Gottschaldt, K.-D., Braeuer, T., Aufmhoff, H., Eirenschmalz, L., Sakellariou, F., Neumann, G., ventura, G., and Cadete, W.: Methane emissions from offshore oil and gas production activities in Gabon and Angola: First results from the airborne METHANE-To-Go campaign 2022, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13551, https://doi.org/10.5194/egusphere-egu23-13551, 2023.

Acting on the significant contribution of methane to climate change, the global methane emission reduction pledge was launched at the 2021 United Nations Climate Change Conference (COP26) and has been signed by more than 100 countries. The majority of anthropogenic methane emissions have been spewed from the energy, waste and agriculture sectors which can be measured with source-specific choice of instruments, measurement platforms and evaluation methods to feed mitigation plans. Maaz Maps (www.maazmaps.com), with more than a decade of experience in methane emission studies, aims to support the global methane pledge with international collaborations by bridging between academia and industry to fill gaps and accelerate the global methane emission reduction efforts. Currently this startup is contracted by GERG (The European Gas Research Group) to scientifically evaluate methane emission reports from several technology providers: results of a measurement campaign performed at a compressor station will be shown. In this campaign, the technology providers applied bottom-up and top-down quantification methods using in-situ or remote sensing techniques. The instruments were either directly operated by walking individuals or installed on various platforms: helicopter, cars, tripods, drones, truck or poles. Various quantification methods including mass balance, tracer method and inverse modelling, correlation factors were applied to quantify sources. In this presentation, we are going to introduce the startup and reconciliation overview of the bottom-up and top-down quantification methods from the campaign. 

How to cite: Maazallahi, H.: Maaz Maps: a science-based startup to accelerate and support the global methane pledge, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-16176, https://doi.org/10.5194/egusphere-egu23-16176, 2023.

More than two thirds of global anthropogenic greenhouse gas (GHG) emissions originate from cities. Urban mitigation policies need a reliable emission data basis to effectively reduce emissions and given inventory uncertainties at the level of single cities, there is growing interest in measurement-based methods to support urban GHG emissions monitoring. Inverse modelling is a measurement-based approach that integrates atmospheric observations with emission inventories, whereby the inventories serve as prior estimates that are subsequently constrained against the observations. While such inverse systems rely on modelling frameworks that typically utilise in situ and/or remote measurements of atmospheric GHG mixing ratios, there is scope for city-scale inverse frameworks to utilise other types of GHG observations, such as flux measurements.

In this study, we investigate such an approach based on a two month field campaign between 15th of May and 20th of July in 2022 in Vienna, Austria. In particular, for the prior information, we use tall-tower eddy covariance observations to constrain the CH₄ emissions within the tower's flux footprint and combine the measurements with 1km x 1km inventory data of the larger city area of Vienna. This refined and measurement-supported inventory serves as a-priori information for both, a Bayesian- and a Phillips-Tikhonov based inversion approach. The observational input for the inversion methods is delivered by MUCCnet (Munich Urban Carbon Column network) instruments consisting of four ground-based, sun-viewing FTIR spectrometers (EM27/SUN), with three of these instruments located on the outskirts of Vienna and one instrument located at the bottom of the tall-tower close to the city center. 

This study investigates the synergetic aspects of two different measurement systems: the eddy-covariance system is particularly sensitive to near field emissions with a range of hundreds of meters upwind of the tower, whereas the ground-based remote sensing instruments observe the differential total column concentration and are therefore sensitive to emissions originating several Kilometers upwind. Applying both measurement systems within a city inversion framework may indeed represent a viable option for further constraining city emissions and improving urban GHG emissions monitoring.

How to cite: Luther, A., Forstmaier, A., Tang, H., Bettinelli, J., Ghaith, G., Aigner, P., Makowski, M., Fasano, E., Meeran, K. M., Leitner, S., Watzinger, A., Matthews, B., and Chen, J.: MUCCnet visiting Vienna: refining inverse model prior information with tall-tower flux measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15369, https://doi.org/10.5194/egusphere-egu23-15369, 2023.

Abstract: Greenhouse gases and associated pollutants (CO, NOx, VOCs, aerosols) are measured from a small airplane, mobile laboratory, and towers.  Through mass balance calculations and comparison to numerical models such as CMAQ-GHG  we estimate the total flux from the cities of Baltimore, MD and Washington, DC.  Emissions inventories were found to underestimate methane emissions substantially and have been improved.  Major sources include leakage in the natural gas delivery system and biogenic processes including landfills.  Measurements with high spatial and temporal resolution reveal hot spots of high concentrations often associated with pollutants such as black carbon (BC) and NO₂ that pose a health hazard in disadvantaged communities. 

How to cite: Dickerson, R., Ren, X., and Karion, A.: "Measurements and models of GHGs and short-lived pollutants in the Baltimore/Washington area: Emissions and environmental justice", EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-121, https://doi.org/10.5194/egusphere-egu23-121, 2023.

Methane’s high Global Warming Potential (GWP) and short atmospheric life relative to carbon dioxide have led to methane mitigation as a cost-effective and realistic near-term action that serves as a bridge to longer-term mitigation options. This paper calculated coal mine methane (CMM) emissions from 636 individual coal mines in Shanxi Province based on the Intergovernmental Panel on Climate Change (IPCC) Tier 2 approach. 5 sets of emission factors were used to compile this bottom-up inventory. Each coal mine is classified into 3 different coal mine gas ranks based on the method issued by the National Coal Mine Safety Administration and the National Energy Administration. Haft-hourly eddy-covariance measurements of methane flux from 1 mine (xhv) over a 5-month period were used to quantify and constrain the high-frequency variation in emissions. From the perspective of probability density, 15.5% of the total data is covered by the boxes overlapping the different bottom-up emissions estimates, while 53.5% of the total data falls in the single box below the floor of the bottom-up measurements. The in-situ measurements offer scaling factors (RATIO correction) for updating the preliminary bottom-up coal mine methane emissions datasets. A statistical approach is applied to individual coal mines by grouping them by coal mine gas rank. From the perspective of cumulative probability, the CMM flux shows a pattern that low gas rank < high gas rank < outburst rank. We have compared the CMM emissions with EDGAR-COAL and GFEI. In 2019, the EDGAR and GFEI inventory results show that methane emissions from coal mines in Shanxi Province are 7.27 Tg and 6.29 Tg, respectively. Our results range from 4.41-7.63 Tg. In Changzhi city, over the region in which this dataset has emissions that EDGAR-COAL and GFEI do not identify the emissions are [44.35,125.60,354.02] and [398.22,1125.81,3185.22] with the unit in ug (m^-2 s^-1), respectively. The values in brackets are results after RATIO correction, corresponding to cumulative percentages 30, 50 and 70 respectively. Over the region that EDGAR-COAL has misidentified coal mines, the emissions are 128.27 ug (m^-2 s^-1). Over the region that EDGAR and our inventory both have emissions, the EDGAR-COAL emissions are 357.65 ug (m^-2 s^-1), while our emissions are about 353.87 ug (m^-2 s^-1). Over the region where GFEI has misidentified coal mines, the emissions are 181.18 ug (m^-2 s^-1). Over the region that GFEI and our inventory both have emissions, the GFEI emissions are 164.04 ug (m^-2 s^-1). There are no regions where we have emissions while GFEI has no emissions in Changzhi city. These facility-level inventories can help identify mitigation opportunities at specific mines, and support the design of more effective policies.

How to cite: Hu, W., Qin, K., He, Q., and Cohen, J. B.: Chinese Coal Mines Methane Emissions Constrained by High-Frequency Measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5036, https://doi.org/10.5194/egusphere-egu23-5036, 2023.

The Upper Silesian Coal Basin in southern Poland belongs to one of the strongest emitting regions of anthropogenic methane (CH₄) in Europe. A major part of these CH₄ emissions is related to the coal mining industry, which are in focus of the METHANE-To-Go-Poland project presented here. For the first time, a unique helicopter towed probe (HELiPOD) was used to capture CH₄ plumes from selected coal mine ventilation shafts. The HELiPOD probe (weight 325 kg, length 5 m) was equipped with a 3D wind anemometer and trace gas in situ instrumentation (Picarro G2401-m and Licor-7700) to measure CH₄ with a high precision (1 ppb) and temporal resolution (up to 40 Hz), which is necessary for a precise calculation of the CH₄ mass flux. In June and October 2022, repeated upwind and downwind probing of the plumes from selected shafts (4 shafts, 16 flights) were performed at different horizontal distances from the source (~500 m - 5 km) and altitudes (~20 m – 2 km). This way, both the inflow amount of CH₄ and the horizontal/vertical dispersion of the CH₄ plumes from the shafts were captured. Depending on wind speed, wind direction and stability, suitable flight patterns were developed for every flight. In addition, two controlled CH₄ releases were successfully carried out to prove the novel measurement concept. Mobile ground-based CH₄ measurements complemented the airborne probing.

In this presentation, mass flux calculations based on measurements from the two airborne CH₄ instruments (with different measurement techniques) will be compared and uncertainties determined. Furthermore, CH₄ mass flux calculations resulting from coinciding satellite measurements (GHGSat: swath width <15 km, spatial resolution <27 m) over the same ventilation shafts combined with high-resolved GEOS-FP wind data are presented. Finally, the uncertainties of the two different top-down approaches (air- and satellite-borne) are compared, in addition to different flight strategies. Comparisons with production data from the Polish coal mine industry are foreseen in near future (bottom-up approach). Subsequently, the same kind of airborne concept is envisaged for the METHANE-To-Go-Oman field experiment in autumn 2023, which will focus on CH₄ emissions from the on-shore oil and gas exploration and production in Oman. Our collected data, funded by the International Methane Emissions Observatory (IMEO), will help coal, oil and gas companies as well as governments, to prioritize their CH₄ emission mitigation strategies, actions and policies.

How to cite: Huntrieser, H., Förster, E., Lichtenstern, M., Pätzold, F., Bretschneider, L., Lampert, A., Necki, J., Jagoda, P., Taupin, Q., Holl, D., and Roiger, A.: Quantifying methane emissions from industrial activities: A novel helicopter-borne application for coal mine ventilation shafts in Poland and perspectives, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9152, https://doi.org/10.5194/egusphere-egu23-9152, 2023.

Methane CH₄ is an important anthropogenic greenhouse gas and its rising concentration in the atmosphere contributes significantly to global warming. Satellite measurements of the column-averaged dry-air mole fraction of atmospheric methane, denoted as XCH₄, can be used to provide information about the location of methane sources and on their emissions, which can help to improve emission inventories and review policies to mitigate climate change.   

The Sentinel-5 Precursor (S5P) satellite with the TROPOspheric Monitoring Instrument (TROPOMI) onboard was launched in October 2017 into a sun-synchronous orbit with an equator crossing time of 13:30. TROPOMI measures reflected solar radiation in different wavelength bands to generate various data products and combines daily global coverage with high spatial resolution. TROPOMI's observations in the shortwave infrared (SWIR) spectral range yield methane with a horizontal resolution of typically 5.5 x 7 km². 

We used a monthly XCH₄ data set (2018-2021) generated with the WFM-DOAS retrieval algorithm, developed at the University of Bremen, to detect regions with temporally persistent, locally enhanced XCH₄. At first, we applied a spatial high-pass filter to the XCH₄ data set to filter out the large-scale methane fluctuations. The resulting anomaly ΔXCH₄ maps show the difference of the local XCH₄ values compared to its surroundings. We then analyzed the monthly anomaly maps to identify potential source regions with persistent XCH₄ enhancements by utilizing different filter criteria, such as the number of months in which the local methane anomalies ΔXCH₄ must exceed certain threshold values. As a next step, we used a simple mass balance method to estimate the monthly emissions and the corresponding uncertainties of the detected potential source regions from the monthly averaged XCH₄ maps. In the last step, we interpreted the emissions of the potential source regions in terms of the source type, by comparing the detected potential source regions with emission databases based on a spatial analysis. 

In this presentation, the algorithm and initial results concerning the detection of regions with temporally persistent, local XCH₄ enhancements, originating from localized potential methane sources (e.g., wetlands, coal mining areas, oil and gas fields) are presented.     

How to cite: Vanselow, S., Schneising-Weigel, O., Buchwitz, M., Bovensmann, H., and Burrows, J. P.: Detection of local atmospheric methane enhancements by analyzing Sentinel-5 Precursor satellite data, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-9174, https://doi.org/10.5194/egusphere-egu23-9174, 2023.

Canada was an early adopter of methane regulation in the oil and gas sector, and recently announced a more ambitious goal to reduce 75% of methane emissions by 2030. New stricter methane regulations should also help reduce loading of air pollutants typically associated with methane emissions (H₂S, VOCs, ozone). To examine regional emission trends and to derive an inventory estimate for Canada’s upstream oil and gas sector, we measured methane emissions at 6650 sites across six major oil and gas producing regions in Canada. Our research suggests that methane emissions from the oil and gas industry are underestimated in Canada by ~1.5. For Canada’s largest producing province, Alberta, we found a greater than 1000-fold variation in methane intensity per unit of fossil energy production within the cohort of oil and gas producers. Producer self-published methane emission intensities in ESG materials showed a low bias and tended to mirror regulatory submissions that require reporting only on specific source types. Our measurements suggest that methane-associated pollutants produced by oil and gas activities are also underestimated and communities near these activities may face higher loading of methane-accessory contaminants than might be predicted by Canada’s National Pollutant Release Inventory (NPRI). Using accepted pollutant emission factors, reported flaring and other combustion activity, the federal methane inventory, and our methane measurements, we generated air quality exposure maps reflecting air pollutant loads on Canadian communities. Stricter methane regulation has the potential to significantly decrease methane, but also pollutant loads in several heavy oil communities including the Lloydminster - Bonnyville area.

How to cite: Lavoie, M., Risk, D., MacKay, K., and Bourlon, E.: Underestimation of reported methane emissions, and air pollutant loadings, from upstream oil and gas activities in Canada, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10259, https://doi.org/10.5194/egusphere-egu23-10259, 2023.

Canada is the third largest oil and gas producer, with over 500,000 active and inactive wells, mostly located in the Western Canada Sedimentary Basin (WCSB). A large, undetermined fraction of Canada’s GHG emissions emanate from oil and gas infrastructure. Governments and industry are all committed to immediately reducing methane leaks to the atmosphere from surface casing vent flows (SCVF) and ground migration (GM) of both new and old wells. Methane carbon isotopic composition offers insight into the source of unwanted gas emissions. A geospatial tool would help to attribute and reduce GHG emissions from contour maps of ẟ¹³C of methane and other hydrocarbons of production, SCVF, and GM gases across the WCSB. These “Isoscapes” of production gases vary systematically, reflecting the local geology. SCVF and GM isoscapes are offset from the production ones because the SCVF most often are shallower than the target formations, and the GM gas may be oxidized in soils. The difference between the production and SCVF isoscapes can be used to attribute methane emissions from tanks and production infrastructure, compared to leaks from the wells themselves. The isoscapes directly facilitate the plugging of problem wells.  The maps are based on over 3,000 locations where we used isotope fingerprinting (i.e., Rowe & Muehlenbachs, 1999) to identify the source depth of a leak.  Regulatory measurements mandate that the leaks are sealed at their source depth, greatly adding to the cost of plugging any well. The SCVF isoscapes suggest the likely source depth of an unsampled leaking well, thus greatly simplifying its remediation. Applying such information beyond a local case study may contribute to accounting for the GH contribution from regional oil and gas activities in Canada and elsewhere.

Reference

Rowe, D., & Muehlenbachs, A. (1999). Low-temperature thermal generation of hydrocarbon gases in shallow shales. Nature, 398(6722), 61­-63.

How to cite: Gonzalez Arismendi, G. and Muehlenbachs, K.: A proposal to use “Isoscapes” of fugitive gases from oil and gas wells to facilitate the reduction and attribution of methane emissions and plugging of faulty wells, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10636, https://doi.org/10.5194/egusphere-egu23-10636, 2023.

The oil and gas (O&G) sector contributes significantly to the anthropogenic part of the methane cycle in the atmosphere while having the most effective opportunities for emission mitigation with technically feasible and cost-effective options. Romania is a key O&G producer within the EU Region of Transylvania with its active gas fields being in the focus of the second measurement campaign in the ROMEO project. Teams from European collaborations were deploying various techniques (GPM, OTM-33A, High Flow Sampler, Tracer release) for quantifications of the methane emission rates. In June of 2021, AGH deployed the large-scale flux chamber with help of scientists from  UBB, Romania,  and in cooperation with local O&G operator – Rom-Gas. Construction was designed and built to be used in the case of small gas installations like the single Christmas tree and was tested intensively during this campaign. A hemispheric structure with a diameter of 6 meters and volume of approximately 55 m³ was used to check the tightness of different gas wells in suitable conditions (size, terrain, meteorology). The methane concentration increase was measured by the OA-ICOS technique. We used an LGR MGGA-918 analyser while additional airflow and air mixing inside the chamber were provided with additional ventilators.

In this presentation, methane emission rates calculations based on deployments of large-scale flux chambers in Transylvania will be compared to other techniques. Verification of the chamber was developed using controlled release tests of methane and acetylene. Moreover, the estimated uncertainty of the measurement technique will be presented. Finally, the potential for use of a large-scale flux chamber as a direct ground based measurement technique and complementary to other direct and indirect techniques will be discussed.

The research results presented in this paper have been developed with the use of equipment financed from the funds of the "Excellence Initiative - Research University" program at AGH University of Science and Technology. The authors thank all the members of the ROMEO campaign, in particular, Thomas Roeckmann for providing an opportunity to be part of this measurement campaign.

How to cite: Jagoda, P., Nęcki, J., Bartyzel, J., Radovici, A., Mereuta, A., Roeckmann, T., and Figura, A.: Application of the large-scale flux chamber for quantification of methane release rate at Transylvanian gas fields., EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11773, https://doi.org/10.5194/egusphere-egu23-11773, 2023.

Methane (CH₄) is a potent greenhouse gas but its sources remain poorly quantified in the Eastern Mediterranean and Middle East (EMME) region where major oil and gas production takes place. Light alkanes, such as ethane (C₂H₆), are co-emitted with CH₄ by oil and gas activities and are promising tracers for quantifying the methane emissions from this sector. Cyprus is an ideal location for studying the composition of regional air masses and for characterizing different emission source signatures at a regional scale. A Picarro G2401 greenhouse gas analyzer and two field-based Gas Chromatography Flame Ionization Detectors (GC-FID) for Non-Methane Hydrocarbons (NMHC) measurements were deployed during two campaigns, one in “urban” (Nicosia) and one in “regional background” (Cape Greko) environment respectively. The campaign at the regional background site consisted in continuous methane and NMHCs (C2-C12) observations using a mobile laboratory that was deployed at the south-eastern edge of the island between December 2021 and February 2022. This location was chosen to capture airmasses of remote south and eastern origin, uninfluenced by local sources. We use these observations to 1) evaluate the significance of long-range transported versus local sources in Cyprus, 2) identify and document regional anthropogenic methane sources, and 3) assess the accuracy of the EDGAR sectoral emission inventory over EMME. Positive Matrix Factorization (PMF) analysis of the NMHC dataset resulted in the identification of four distinct sources namely tropospheric background, urban, heavy oil combustion, and transported from Middle East. The latest occurred during three distinct episodes and on average, had the highest NMHC concentrations. Generally, the different urban and regional signatures/sources displayed good and variable correlations between CH₄ and C2 to C6-NMHCs. By investigating the PMF results together with CH4 concentrations and an atmospheric dispersion model (FLEXPART), we provide a comprehensive characterization of the pollution sources at regional scale over the Eastern Mediterranean region.

How to cite: Germain-Piaulenne, E., Paris, J.-D., Bourtsoukidis, E., Quehe, P.-Y., Michael Pikridas, M., Desservettaz, M., Baisnee, D., Liu, Y., Gros, V., and Sciare, J.: Methane source identification using Non-Methane Hydrocarbon (NMHC) source apportionment in the Eastern Mediterranean and Middle East region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-13865, https://doi.org/10.5194/egusphere-egu23-13865, 2023.

Methane (CH₄) is the second greatest contributor to climate forcing after carbon dioxide (CO₂).  Methane has a considerably shorter atmospheric lifetime compared to CO₂ (12 yr c.f. 300-1000 yr) but a higher warming potential in the atmosphere (GWP_100yr 28, (IPCC, 2014)). Most anthropogenic emissions come from landfills, wastewater treatment plants, leaks in the fossil fuel supply chain and ruminant livestock.  The reduction of anthropogenic methane emissions is key to maintaining the feasibility of the Paris Agreement. The Global Methane Pledge launched at COP26 aims to reduce methane emissions by 30% relative to 2020 by 2030. Urban areas are an ideal target to reduce methane emissions given that they account for around 20% of the total emissions whilst they occupy only 3% of the land surface. Urban methane mitigations plans are proven to have a high impact reducing GHG emissions and bringing co-benefits in public health through improvements in air quality.

Australia is a signatory to both the Paris Agreement and the Global Methane Pledge and have an important potential emission reduction in urban areas. Melbourne is the second most populous city in Australia with over 5 million people (around 1/5 of Australia’s population) and it is projected to become the most populated by 2050. A recent study attempted to improve methane emission inventories for Melbourne using an inversion system, global emission data and atmospheric measurements (Shahrokhi , 2022).  Their results showed that current emission datasets do not accurately represent the spatial distribution and total estimates of methane emissions over Melbourne. Hence, an improved emission inventory is required for Melbourne. This will reduce the uncertainty and limitations of current methane emission estimates and support the formulation of effective emissions mitigation plans. Essential to this is the expansion of the Melbourne urban observational network, which is currently too sparse to accurately detect emissions. Here we present our preliminary progress on the development of a comprehensive methane observation network. This project aims to combine different measurement techniques to achieve a better representation of methane mole fraction variability in the Melbourne region, to inform inverse modelling estimates of emissions. We use a combination of mobile and stationary ground observations in key parts of the city to better capture and represent methane emissions. Future work includes the comparison of high precision analysers with low-cost sensors, improvement of source attribution by measurements of methane isotopes and other tracers, and the use of “AirCore” technology to obtain vertical methane profiles.

References

IPCC, 2014: Climate Change 2014: Synthesis Report. Contribution of Working Groups I, II and III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Core Writing Team, R.K. Pachauri and L.A. Meyer (eds.)]. IPCC, Geneva, Switzerland, 151 pp.

Shahrokhi, N. 2022. Regional Methane Inversion for Melbourne, Australia, using in-situ measurements. Online poster [accessed 10 Jan 2022]. Available from: https://agu2022fallmeeting-agu.ipostersessions.com/default.aspx?s=2F-7B-00-39-98-DC-28-09-C3-90-81-25-D7-44-E2-D2#

How to cite: Ramirez Gamboa, J., Loh, Z., Stavert, A., Krummel, P., Shahrokhi, N., Trudinger, C., Caldow, C., Spencer, D., and Roulston, C.: Supporting Methane Mitigation Efforts by Improving Urban-scale Methane Emission Estimates in Melbourne, Australia. Part 2: Developing the methane observation network for the Melbourne region, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-10725, https://doi.org/10.5194/egusphere-egu23-10725, 2023.