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Towards accurate methane point-source quantification from high-resolution 2-D plume imagery

Jongaramrungruang, Siraput and Frankenberg, Christian and Matheou, Georgios and Thorpe, Andrew K. and Thompson, David R. and Kuai, Le and Duren, Riley M. (2019) Towards accurate methane point-source quantification from high-resolution 2-D plume imagery. Atmospheric Measurement Techniques, 12 (12). pp. 6667-6681. ISSN 1867-8548. https://resolver.caltech.edu/CaltechAUTHORS:20200103-110843259

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Abstract

Methane is the second most important anthropogenic greenhouse gas in the Earth climate system but emission quantification of localized point sources has been proven challenging, resulting in ambiguous regional budgets and source category distributions. Although recent advancements in airborne remote sensing instruments enable retrievals of methane enhancements at an unprecedented resolution of 1–5 m at regional scales, emission quantification of individual sources can be limited by the lack of knowledge of local wind speed. Here, we developed an algorithm that can estimate flux rates solely from mapped methane plumes, avoiding the need for ancillary information on wind speed. The algorithm was trained on synthetic measurements using large eddy simulations under a range of background wind speeds of 1–10 m s⁻¹ and source emission rates ranging from 10 to 1000 kg h⁻¹. The surrogate measurements mimic plume mapping performed by the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and provide an ensemble of 2-D snapshots of column methane enhancements at 5 m spatial resolution. We make use of the integrated total methane enhancement in each plume, denoted as integrated methane enhancement (IME), and investigate how this IME relates to the actual methane flux rate. Our analysis shows that the IME corresponds to the flux rate nonlinearly and is strongly dependent on the background wind speed over the plume. We demonstrate that the plume width, defined based on the plume angular distribution around its main axis, provides information on the associated background wind speed. This allows us to invert source flux rate based solely on the IME and the plume shape itself. On average, the error estimate based on randomly generated plumes is approximately 30 % for an individual estimate and less than 10 % for an aggregation of 30 plumes. A validation against a natural gas controlled-release experiment agrees to within 32 %, supporting the basis for the applicability of this technique to quantifying point sources over large geographical areas in airborne field campaigns and future space-based observations.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.5194/amt-12-6667-2019DOIArticle
ORCID:
AuthorORCID
Frankenberg, Christian0000-0002-0546-5857
Thorpe, Andrew K.0000-0001-7968-5433
Thompson, David R.0000-0003-1100-7550
Kuai, Le0000-0001-6406-1150
Duren, Riley M.0000-0003-4723-5280
Additional Information:© 2019 Author(s). This work is distributed under the Creative Commons Attribution 4.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 25 Apr 2019 – Discussion started: 06 May 2019 – Revised: 18 Oct 2019 – Accepted: 22 Oct 2019 – Published: 17 Dec 2019. This work is part of SJ's NASA Earth and Space Science Fellowship (NESSF). We acknowledge the Resnick Sustainability Institute at Caltech for their kind support with computing resources. This work was supported in part by NASA's Carbon Monitoring System (CMS) Prototype Methane Monitoring System for California. We also thank NASA's Earth Science Division, particularly Jack Kaye, for continued support of AVIRIS-NG and HyTES methane science. Additional funding was provided to JPL by the California Air Resources Board under ARB-NASA agreement 15RD028 and Space Act agreement 82-19863 as well as the California Energy Commission under CEC-500-15-004. A portion of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration (NNN12AA01C). We thank the AVIRIS-NG team and colleagues at the Pacific Gas and Electric Company for their support for controlled-release experiments. Code and data availability: AVIRIS-NG data are publicly available via the AVIRIS-NG data portal by JPL via https://aviris-ng.jpl.nasa.gov/benchmark_methane_data.html (last access: 4 December 2019); HyTES L2 and L3 data are available for ordering free of charge from the HyTES data portal by JPL at https://hytes.jpl.nasa.gov/order (last access: 4 December 2019). Author contributions: SJ performed the analysis and wrote the paper, with the overall research objectives advised by CF. GM ran the LES model, provided output, and guided the analysis; AT, RD, EK, and DT provided the AVIRIS-NG and HyTES datasets and supported the writing and data analysis. The authors declare that they have no conflict of interest. This research has been supported by NASA (grant no. 80NSSC18K1350). Review statement: This paper was edited by Christoph Kiemle and reviewed by two anonymous referees.
Group:Resnick Sustainability Institute
Funders:
Funding AgencyGrant Number
NASA Earth and Space Science FellowshipUNSPECIFIED
California Air Resources Board15RD028
NASA82-19863
California Energy CommissionCEC-500-15-004
NASANNN12AA01C
NASA/JPL/CaltechUNSPECIFIED
NASA80NSSC18K1350
Issue or Number:12
Record Number:CaltechAUTHORS:20200103-110843259
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200103-110843259
Official Citation:Jongaramrungruang, S., Frankenberg, C., Matheou, G., Thorpe, A. K., Thompson, D. R., Kuai, L., and Duren, R. M.: Towards accurate methane point-source quantification from high-resolution 2-D plume imagery, Atmos. Meas. Tech., 12, 6667–6681, https://doi.org/10.5194/amt-12-6667-2019, 2019
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100501
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:05 Jan 2020 00:09
Last Modified:05 Jan 2020 00:09

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