Estimating Regional Methane Emissions Through Atmospheric Measurements and Inverse Modeling.

2019 ◽  
Author(s):  
Cosmin Safta ◽  
Ray Bambha ◽  
Hope Michelsen
Keyword(s):  
Inverse Modeling ◽  
Methane Emissions ◽  
Atmospheric Measurements

scholarly journals Atmospheric Inverse Modeling via Sparse Reconstruction

2016 ◽  
Author(s):  
Nils Hase ◽  
Scot M. Miller ◽  
Peter Maaß ◽  
Justus Notholt ◽  
Mathias Palm ◽  
...  
Keyword(s):  
Inverse Problems ◽  
Inverse Modeling ◽  
Hot Spots ◽  
Atmospheric Science ◽  
Methane Emissions ◽  
Point Sources ◽  
Sparse Reconstruction ◽  
Atmospheric Measurements ◽  
Localized Structures ◽  
Ill Posed

Abstract. Many applications in atmospheric science involve ill-posed inverse problems. A crucial component of many inverse problems is the proper formulation of a priori knowledge about the unknown parameters. In most cases, this knowledge is expressed as a Gaussian prior. This formulation often performs well at capturing smoothed, large-scale processes but is often ill-equipped to capture localized structures like large point sources or localized hot spots. Over the last decade, scientists from a diverse array of applied math and engineering fields have developed sparse reconstruction techniques to identify localized structures. In this study we present a new regularization approach for ill-posed inverse problems in atmospheric science. It is based on Tikhonov regularization with sparsity constraint and allows bounds on the parameters. We enforce sparsity using a dictionary representation system. We analyze its performance in an atmospheric inverse modeling scenario by estimating anthropogenic US methane emissions from simulated atmospheric measurements. Different measures indicate that our sparse reconstruction approach is better able to capture large point sources or localized hot spots than other methods commonly used in atmospheric inversions. It captures the overall signal equally well, but adds details on the grid scale. This can be of great value in many research projects. We show an example for source estimation of synthetic methane emissions from the Barnett shale formation.

scholarly journals Top-down estimate of methane emissions in California using a mesoscale inverse modeling technique: The San Joaquin Valley

2017 ◽  
Vol 122 (6) ◽  
pp. 3686-3699 ◽  
Author(s):  
Yu Yan Cui ◽  
Jerome Brioude ◽  
Wayne M. Angevine ◽  
Jeff Peischl ◽  
Stuart A. McKeen ◽  
...  
Keyword(s):  
Inverse Modeling ◽  
Methane Emissions ◽  
San Joaquin Valley ◽  
Modeling Technique ◽  
Top Down

Using atmospheric in-situ measurements of 13CH4 to investigate methane emissions in Western Canada

2021 ◽  
Author(s):  
Felix Vogel ◽  
Sebastien Ars ◽  
Karlis Muehlenbachs ◽  
Gabriela Gonzalez Arismendi ◽  
Doug Worthy
Keyword(s):  
Fossil Fuels ◽  
Oil And Gas ◽  
Dispersion Model ◽  
Methane Emissions ◽  
Isotopic Signature ◽  
Atmospheric Measurements ◽  
Hysplit Model ◽  
Contour Maps ◽  
The Government ◽  
Government Of Canada

<p>The climate change impact of methane is significant and the recent increase in its atmospheric concentrations raises great concerns. Across Canada, methane emissions are unevenly distributed with a large part attributed to the Western Canadian Sedimentary Basin (WCSB), which is the fourth largest reserve of fossil fuels in the world. The WCSB extends from northeastern British Columbia to southwestern Manitoba, encompassing Alberta and southern Saskatchewan. The extraction of  hydrocarbons mostly takes place in the provinces of Alberta and Saskatchewan and is a large source of methane.</p><p>According to recent international agreements, the Government of Canada has committed to reducing methane emissions by 40 to 45% by 2025 based on 2012 levels. However, a recent study using atmospheric measurements of methane concentrations in the region showed that methane emissions from the oil and gas sector might be nearly twice that reported in Canada’s National Inventory (Chan et al., 2020). More investigations are required to better understand the discrepancy between these two estimates.</p><p>In this study, we use atmospheric observations of δ<sup>13</sup>C measured successively at three locations across the WCSB between 2016 and 2020 to help identify the influence of different types of methane sources across the provinces of Alberta and Saskatchewan. We compare our atmospheric measurements with compilations and isotope contour maps of fugitive methane from energy facilities across the basin. Combining these measurements with trajectories computed with the HYSPLIT model developed by NOAA, we show a gradient in the methane isotopic signature across Alberta: methane being more depleted in southwestern Saskatchewan than northwestern Alberta. We also used the HYSPLIT5-STILT dispersion model to derive footprints during our measurements and estimate methane contributions of these two provinces using an optimization based on the isotopic measurements.</p><p> </p><p>Chan et al. 2020: </p>

scholarly journals Four-dimensional variational data assimilation for inverse modeling of atmospheric methane emissions: Analysis of SCIAMACHY observations

2008 ◽  
Vol 113 (D17) ◽  
Author(s):  
Jan Fokke Meirink ◽  
Peter Bergamaschi ◽  
Christian Frankenberg ◽  
Monica T. S. d'Amelio ◽  
Edward J. Dlugokencky ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Inverse Modeling ◽  
Methane Emissions ◽  
Variational Data Assimilation ◽  
Atmospheric Methane

scholarly journals Quantifying the loss of processed natural gas within California's South Coast Air Basin using long-term measurements of ethane and methane

2016 ◽  
Vol 16 (22) ◽  
pp. 14091-14105 ◽  
Author(s):  
Debra Wunch ◽  
Geoffrey C. Toon ◽  
Jacob K. Hedelius ◽  
Nicholas Vizenor ◽  
Coleen M. Roehl ◽  
...  
Keyword(s):  
Natural Gas ◽  
Methane Emissions ◽  
South Coast ◽  
Rapid Decline ◽  
Atmospheric Measurements ◽  
Time Period ◽  
Emissions Inventories ◽  
South Coast Air Basin ◽  
Atmospheric Trace Gas

Abstract. Methane emissions inventories for Southern California's South Coast Air Basin (SoCAB) have underestimated emissions from atmospheric measurements. To provide insight into the sources of the discrepancy, we analyze records of atmospheric trace gas total column abundances in the SoCAB starting in the late 1980s to produce annual estimates of the ethane emissions from 1989 to 2015 and methane emissions from 2007 to 2015. The first decade of measurements shows a rapid decline in ethane emissions coincident with decreasing natural gas and crude oil production in the basin. Between 2010 and 2015, however, ethane emissions have grown gradually from about 13 ± 5 to about 23 ± 3 Gg yr−1, despite the steady production of natural gas and oil over that time period. The methane emissions record begins with 1 year of measurements in 2007 and continuous measurements from 2011 to 2016 and shows little trend over time, with an average emission rate of 413 ± 86 Gg yr−1. Since 2012, ethane to methane ratios in the natural gas withdrawn from a storage facility within the SoCAB have been increasing by 0.62 ± 0.05 % yr−1, consistent with the ratios measured in the delivered gas. Our atmospheric measurements also show an increase in these ratios but with a slope of 0.36 ± 0.08 % yr−1, or 58 ± 13 % of the slope calculated from the withdrawn gas. From this, we infer that more than half of the excess methane in the SoCAB between 2012 and 2015 is attributable to losses from the natural gas infrastructure.

scholarly journals Top-down estimate of methane emissions in California using a mesoscale inverse modeling technique: The South Coast Air Basin

2015 ◽  
Vol 120 (13) ◽  
pp. 6698-6711 ◽  
Author(s):  
Yu Yan Cui ◽  
Jerome Brioude ◽  
Stuart A. McKeen ◽  
Wayne M. Angevine ◽  
Si-Wan Kim ◽  
...  
Keyword(s):  
Inverse Modeling ◽  
Methane Emissions ◽  
South Coast ◽  
Modeling Technique ◽  
The South ◽  
Top Down ◽  
South Coast Air Basin

scholarly journals A gridded inventory of Canada's anthropogenic methane emissions

2021 ◽  
Author(s):  
Tia R Scarpelli ◽  
Daniel J Jacob ◽  
Michael D Moran ◽  
Frances Reuland ◽  
Deborah Gordon
Keyword(s):  
Oil Sands ◽  
Methane Emissions ◽  
Gas Production ◽  
Western Canada ◽  
Atmospheric Methane ◽  
Source Attribution ◽  
Atmospheric Measurements ◽  
Eastern Canada ◽  
Geospatial Datasets ◽  
Oil Gas

Abstract Canada's anthropogenic methane emissions are reported annually to the United Nations Framework Convention on Climate Change (UNFCCC) through Canada's National Inventory Report (NIR). Evaluation of this policy-relevant inventory using observations of atmospheric methane requires prior information on the spatial distribution of emissions but that information is lacking in the NIR. Here we spatially allocate the NIR methane emissions for 2018 on a 0.1º x 0.1º grid (≈ 10 km x 10 km) for individual source sectors and subsectors, with further resolution by source type for the oil/gas sector, using an ensemble of national and provincial geospatial datasets and including facility-level information from Canada's Greenhouse Gas Reporting Program. The highest emissions are from oil/gas production and livestock in western Canada, and landfills in eastern Canada. We find 11 hotspots emitting more than 1 metric ton h-1 on the 0.1º x 0.1º grid. Oil sands mines in northeast Alberta contribute 3 of these hotspots even though oil sands contribute only 4% of national oil/gas emissions. Our gridded inventory shows large spatial differences with the EDGAR v5 inventory commonly used for inversions of atmospheric methane observations, which may reflect EDGAR's reliance on global geospatial datasets. Comparison of our spatially resolved inventory to atmospheric measurements in oil/gas production fields suggests that the NIR underestimates these emissions. We also find strong spatial overlap between oil/gas, livestock, and wetland emissions in western Canada that may complicate source attribution in inversions of atmospheric data.

scholarly journals Sulfur hexafluoride (SF<sub>6</sub>) emissions in East Asia determined by inverse modeling

2014 ◽  
Vol 14 (9) ◽  
pp. 4779-4791 ◽  
Author(s):  
X. Fang ◽  
R. L. Thompson ◽  
T. Saito ◽  
Y. Yokouchi ◽  
J. Kim ◽  
...  
Keyword(s):  
South Korea ◽  
East Asia ◽  
Inverse Modeling ◽  
North Korea ◽  
Sulfur Hexafluoride ◽  
A Priori ◽  
East Asian ◽  
Atmospheric Measurements ◽  
Per Capita ◽  
Year 2000

Abstract. Sulfur hexafluoride (SF6) has a global warming potential of around 22 800 over a 100-year time horizon and is one of the greenhouse gases regulated under the Kyoto Protocol. Around the year 2000 there was a reversal in the global SF6 emission trend, from a decreasing to an increasing trend, which was likely caused by increasing emissions in countries that are not obligated to report their annual emissions to the United Nations Framework Convention on Climate Change. In this study, SF6 emissions during the period 2006–2012 for all East Asian countries – including Mongolia, China, Taiwan, North Korea, South Korea and Japan – were determined by using inverse modeling and in situ atmospheric measurements. We found that the most important sources of uncertainty associated with these inversions are related to the choice of a priori emissions and their assumed uncertainty, the station network as well as the meteorological input data. Much lower uncertainties are due to seasonal variability in the emissions, inversion geometry and resolution, and the measurement calibration scale. Based on the results of these sensitivity tests, we estimate that the total SF6 emission in East Asia increased rapidly from 2404 ± 325 Mg yr−1 in 2006 to 3787 ± 512 Mg yr−1 in 2009 and stabilized thereafter. China contributed 60–72% to the total East Asian emission for the different years, followed by South Korea (8–16%), Japan (5–16%) and Taiwan (4–7%), while the contributions from North Korea and Mongolia together were less than 3% of the total. The per capita SF6 emissions are highest in South Korea and Taiwan, while the per capita emissions for China, North Korea and Japan are close to global average. During the period 2006–2012, emissions from China and from South Korea increased, while emissions from Taiwan and Japan decreased overall.

scholarly journals Inverse modeling of European CH<sub>4</sub> emissions: sensitivity to the observational network

2010 ◽  
Vol 10 (3) ◽  
pp. 1249-1267 ◽  
Author(s):  
M. G. Villani ◽  
P. Bergamaschi ◽  
M. Krol ◽  
J. F. Meirink ◽  
F. Dentener
Keyword(s):  
Inverse Modeling ◽  
A Priori ◽  
Temporal Distribution ◽  
Sensitivity Study ◽  
European Countries ◽  
Atmospheric Measurements ◽  
North West ◽  
East European ◽  
Annual Total ◽  
Surface Network

Abstract. Inverse modeling is widely employed to provide "top-down" emission estimates using atmospheric measurements. Here, we analyze the dependence of derived CH4 emissions on the sampling frequency and density of the observational surface network, using the TM5-4DVAR inverse modeling system and synthetic observations. This sensitivity study focuses on Europe. The synthetic observations are created by TM5 forward model simulations. The inversions of these synthetic observations are performed using virtually no knowledge on the a priori spatial and temporal distribution of emissions, i.e. the emissions are derived mainly from the atmospheric signal detected by the measurement network. Using the European network of stations for which continuous or weekly flask measurements are available for 2001, the synthetic experiments can retrieve the "true" annual total emissions for single countries such as France within 20%, and for all North West European countries together within ~5%. However, larger deviations are obtained for South and East European countries due to the scarcity of stations in the measurement network. Upgrading flask sites to stations with continuous measurements leads to an improvement for central Europe in emission estimates. For realistic emission estimates over the whole European domain, however, a major extension of the number of stations in the existing network is required. We demonstrate the potential of an extended network of a total of ~60 European stations to provide realistic emission estimates over the whole European domain.

scholarly journals Carbon isotopic characterisation and oxidation of UK landfill methane emissions by atmospheric measurements

2021 ◽  
Vol 132 ◽  
pp. 162-175
Author(s):  
Semra Bakkaloglu ◽  
Dave Lowry ◽  
Rebecca E. Fisher ◽  
James L. France ◽  
Euan G. Nisbet
Keyword(s):  
Methane Emissions ◽  
Atmospheric Measurements ◽  
Carbon Isotopic
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