Airborne visualization and quantification of discrete methane sources in the environment

Tratt, David M.; Buckland, Kerry N.; Hall, Jeffrey L.; Johnson, Patrick D.; Keim, E. R.; Leifer, Ira; Westberg, Karl; Young, Stephen J.

doi:10.1016/j.rse.2014.08.011

Cited by 78 publications

(62 citation statements)

References 66 publications

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“…The methane airborne mapper (MAMAP) retrieves methane in the SWIR at 1.6 µm, similar to SCIAMACHY, but currently lacks imaging capabilities. Imaging spectrometers initially designed for surface remote sensing have been shown to detect methane plumes with horizontal resolution as fine as 1 m either in the SWIR using the strong 2.3 µm band (Roberts et al, 2010;Thorpe et al, 2016) or in the TIR (Tratt et al, 2014;Hulley et al, 2016). These imaging spectrometers such as AVIRIS-NG (SWIR) and MAKO or HyTES (TIR) have much coarser spectral resolution than MAMAP or current satellite instruments (e.g., 5 nm for AVIRIS-NG).…”

Section: Observing Requirements For Regional and Point Sourcesmentioning

confidence: 99%

Satellite observations of atmospheric methane and their value for quantifying methane emissions

et al. 2016

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Abstract. Methane is a greenhouse gas emitted by a range of natural and anthropogenic sources. Atmospheric methane has been measured continuously from space since 2003, and new instruments are planned for launch in the near future that will greatly expand the capabilities of space-based observations. We review the value of current, future, and proposed satellite observations to better quantify and understand methane emissions through inverse analyses, from the global scale down to the scale of point sources and in combination with suborbital (surface and aircraft) data. Current global observations from Greenhouse Gases Observing Satellite (GOSAT) are of high quality but have sparse spatial coverage. They can quantify methane emissions on a regional scale (100-1000 km) through multiyear averaging. The Tropospheric Monitoring Instrument (TROPOMI), to be launched in 2017, is expected to quantify daily emissions on the regional scale and will also effectively detect large point sources. A different observing strategy by GHGSat (launched in June 2016) is to target limited viewing domains with very fine pixel resolution in order to detect a wide range of methane point sources. Geostationary observation of methane, still in the proposal stage, will have the unique capability of mapping source regions with high resolution, detecting transient "super-emitter" point sources and resolving diurnal variation of emissions from sources such as wetlands and manure. Exploiting these rapidly expanding satellite measurement capabilities to quantify methane emissions requires a parallel effort to construct high-quality spatially and sectorally resolved emission inventories. Partnership between top-down inverse analyses of atmospheric data and bottom-up construction of emission inventories is crucial to better understanding methane emission processes and subsequently informing climate policy.

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Section: Observing Requirements For Regional and Point Sourcesmentioning

confidence: 99%

Satellite observations of atmospheric methane and their value for quantifying methane emissions

et al. 2016

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“…Many different sets of assumptions and sampling strategies are employed, but the overall goal is to sample the main dispersion routes of the surface emissions as they make their way into the overlying atmosphere after first accumulating near the surface. The scales that can be addressed by this method are from a few kilometers (Alfieri et al, 2010;Hacker et al, 2016;Hiller et al, 2014;Tratt et al, 2014) to tens of kilometers (Caulton et al, 2014;Karion et al, 2013;Wratt et al, 2001) to even potentially hundreds of kilometers (Beswick et al, 1998;Chang et al, 2014), and this approach has been the focus of recent measurements in natural gas production basins. These basins present a source apportionment challenge in that emissions from multiple sources (agriculture, oil and gas wells, geologic seepage, etc.)…”

Section: Introductionmentioning

confidence: 99%

Application of Gauss's theorem to quantify localized surface emissions from airborne measurements of wind and trace gases

et al. 2017

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Abstract. Airborne estimates of greenhouse gas emissions are becoming more prevalent with the advent of rapid commercial development of trace gas instrumentation featuring increased measurement accuracy, precision, and frequency, and the swelling interest in the verification of current emission inventories. Multiple airborne studies have indicated that emission inventories may underestimate some hydrocarbon emission sources in US oil-and gas-producing basins. Consequently, a proper assessment of the accuracy of these airborne methods is crucial to interpreting the meaning of such discrepancies. We present a new method of sampling surface sources of any trace gas for which fast and precise measurements can be made and apply it to methane, ethane, and carbon dioxide on spatial scales of ∼ 1000 m, where consecutive loops are flown around a targeted source region at multiple altitudes. Using Reynolds decomposition for the scalar concentrations, along with Gauss's theorem, we show that the method accurately accounts for the smallerscale turbulent dispersion of the local plume, which is often ignored in other average "mass balance" methods. With the help of large eddy simulations (LES) we further show how the circling radius can be optimized for the micrometeorological conditions encountered during any flight. Furthermore, by sampling controlled releases of methane and ethane on the ground we can ascertain that the accuracy of the method, in appropriate meteorological conditions, is often better than 10 %, with limits of detection below 5 kg h −1 for both methane and ethane. Because of the FAA-mandated minimum flight safe altitude of 150 m, placement of the aircraft is critical to preventing a large portion of the emission plume from flowing underneath the lowest aircraft sampling altitude, which is generally the leading source of uncertainty in these measurements. Finally, we show how the accuracy of the method is strongly dependent on the number of sampling loops and/or time spent sampling the source plume.

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“…While other researchers have used far more sophisticated and expensive systems for mapping methane [35], the routine implementation of these systems for monitoring has not occurred. To make meaningful progress on identification and quantification of methane emissions from landfills and natural gas infrastructure, monitoring systems that are easier and less expensive to deploy are needed.…”

Section: Discussionmentioning

confidence: 99%

“…One demonstration trial involved surveying a section of a pipeline in Alaska [32]. Some applications were mainly based on using a single sensor, such as laser sensor [33] gas filter [34] and hyperspectral imaging technology [35], while others used sensor fusion algorithms to fuse the measurements gathered from a laser sensor and an electro-optical sensor [36]. Lehmann et al [37] reported a more specific use of UAV for remote sensing of methane concentration using camera system for environmental studies.…”

Section: Introductionmentioning

confidence: 99%

Low-Altitude Aerial Methane Concentration Mapping

2017

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Detection of leaks of fugitive greenhouse gases (GHGs) from landfills and natural gas infrastructure is critical for not only their safe operation but also for protecting the environment. Current inspection practices involve moving a methane detector within the target area by a person or vehicle. This procedure is dangerous, time consuming, labor intensive and above all unavailable when access to the desired area is limited. Remote sensing by an unmanned aerial vehicle (UAV) equipped with a methane detector is a cost-effective and fast method for methane detection and monitoring, especially for vast and remote areas. This paper describes the integration of an off-the-shelf laser-based methane detector into a multi-rotor UAV and demonstrates its efficacy in generating an aerial methane concentration map of a landfill. The UAV flies a preset flight path measuring methane concentrations in a vertical air column between the UAV and the ground surface. Measurements were taken at 10 Hz giving a typical distance between measurements of 0.2 m when flying at 2 m/s. The UAV was set to fly at 25 to 30 m above the ground. We conclude that besides its utility in landfill monitoring, the proposed method is ready for other environmental applications as well as the inspection of natural gas infrastructure that can release methane with much higher concentrations.

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Airborne visualization and quantification of discrete methane sources in the environment

Cited by 78 publications

References 66 publications

Satellite observations of atmospheric methane and their value for quantifying methane emissions

Satellite observations of atmospheric methane and their value for quantifying methane emissions

Application of Gauss's theorem to quantify localized surface emissions from airborne measurements of wind and trace gases

Low-Altitude Aerial Methane Concentration Mapping

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