A Low-Cost System for Measuring Horizontal Winds from Single-Engine Aircraft

Conley, Stephen; Faloona, I. C.; Lenschow, Donald H.; Karion, A.; Sweeney, Colm

doi:10.1175/jtech-d-13-00143.1

Cited by 42 publications

(35 citation statements)

References 20 publications

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“…This instrument error affected some, but not all of our wind measurements. Data reported here supersede those reported in a retracted paper (Ren, Hall, et al, ); see section S1 of the supporting information (SI) (Conley et al, ; Healey et al, ; Mueller & Wagner, ).…”

Section: Experimental and Methodssupporting

confidence: 69%

Methane Emissions from the Marcellus Shale in Southwestern Pennsylvania and Northern West Virginia Based on Airborne Measurements

et al. 2019

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Natural gas production in the United States has increased rapidly over the past decade, along with concerns about methane (CH4) fugitive emissions and its climate impacts. Quantification of CH4 emissions from oil and natural gas (O&NG) operations is important for establishing scientifically sound policies for mitigating greenhouse gases. We use the aircraft mass balance approach for three flight experiments in August and September 2015 to estimate CH4 emissions from O&NG operations over the southwestern Marcellus Shale. We estimate a mean CH4 emission rate as 21.2 kg/s with 28% coming from O&NG operations. The mean CH4 emission rate from O&NG operations was estimated to be 1.1% of total NG production. The individual best‐estimate emission rates from the three flight experiments ranged from 0.78 to 1.5%, with overall limits of 0% and 3.5%. These emission rates are at the low end of other top‐down studies, but consistent with the few observational studies in the Marcellus Shale region as well as the U.S. Environmental Protection Agency CH4 inventory. A substantial source of CH4 (~70% of observed CH4 emissions) was found to contain little ethane, possibly due to coalbed CH4 emitted either directly from coal mines or from wells drilled through coalbed layers in O&NG operations. Recent regulations requiring capture of gas from the completion‐venting step of hydraulic fracturing appear to have reduced the atmospheric release of CH4. Our study suggests that for a 20‐year time scale, energy derived from the combustion of natural gas extracted from this region likely exerts a net climate benefit compared to coal.

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Section: Experimental and Methodssupporting

confidence: 69%

Methane Emissions from the Marcellus Shale in Southwestern Pennsylvania and Northern West Virginia Based on Airborne Measurements

et al. 2019

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“…The airborne detection system is flown on a fixed wing single-engine Mooney aircraft, extensively modified for research as described in Conley et al (2014). Ambient air is collected through ∼ 5 m of tubing (Kynar, Teflon, and stainless steel) that protrudes out of backward-facing aluminum inlets mounted below the right wing.…”

Section: Airborne Instrumentationmentioning

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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“…Total uncertainty is estimated at ±1.0 ppb. Wind speed and direction were measured at 1 Hz with estimated uncertainty at ±1 m/s with a differential GPS approach as described by Conley et al [2014]. Ozone was measured with a 2B Technologies analyzer.…”

Section: Aircraft Flights and Instrumentationmentioning

confidence: 99%

Fugitive emissions from the Bakken shale illustrate role of shale production in global ethane shift

Kort

Smith

Murray

et al. 2016

Geophysical Research Letters

106

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Ethane is the second most abundant atmospheric hydrocarbon, exerts a strong influence on tropospheric ozone, and reduces the atmosphere's oxidative capacity. Global observations showed declining ethane abundances from 1984 to 2010, while a regional measurement indicated increasing levels since 2009, with the reason for this subject to speculation. The Bakken shale is an oil and gas‐producing formation centered in North Dakota that experienced a rapid increase in production beginning in 2010. We use airborne data collected over the North Dakota portion of the Bakken shale in 2014 to calculate ethane emissions of 0.23 ± 0.07 (2σ) Tg/yr, equivalent to 1–3% of total global sources. Emissions of this magnitude impact air quality via concurrent increases in tropospheric ozone. This recently developed large ethane source from one location illustrates the key role of shale oil and gas production in rising global ethane levels.

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A Low-Cost System for Measuring Horizontal Winds from Single-Engine Aircraft

Cited by 42 publications

References 20 publications

Methane Emissions from the Marcellus Shale in Southwestern Pennsylvania and Northern West Virginia Based on Airborne Measurements

Methane Emissions from the Marcellus Shale in Southwestern Pennsylvania and Northern West Virginia Based on Airborne Measurements

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

Fugitive emissions from the Bakken shale illustrate role of shale production in global ethane shift

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