Deducing Ground-to-Air Emissions from Observed Trace Gas Concentrations: A Field Trial

Flesch, Thomas K.; Wilson, Joel; Harper, Lowry A.; Crenna, Brian P.; Sharpe, R. R.

doi:10.1175/1520-0450(2004)043<0487:dgefot>2.0.co;2

Cited by 306 publications

(240 citation statements)

References 23 publications

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“…Laser-based criteria are applied to remove potentially inaccurate or unrepresentative line averaged concentration values, especially when observations correspond to <5 min of a 10-min period, R 2 min (a measure of observed concentration relative to internal cell reference) is <98, and/or when reported light levels (an operating, unitless parameter related to the signal level of the returning laser beam) falls outside an operating range; 3000 to 11 000. Criteria applied to the BLS output, intended to remove error-prone periods, have been applied in previous studies and are based on low wind speed periods (Flesch et al, 2014), periods of extreme atmospheric stratification (Flesch et al, 2004), where actual wind conditions violate WindTrax assumptions, and/or when the fractional coverage (footprint) of the downwind OPL measurement relative to the source area is marginal (Flesch et al, 2007). The application of the criteria removes outliers in the emission dataset (WindTrax output) unique to location and conditions during measurement periods.…”

Section: Resultsmentioning

confidence: 99%

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Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Tomkins

Charmley

2015

Animal

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Methane (CH 4 ) emissions associated with beef production systems in northern Australia are yet to be quantified. Methodologies are available to measure emissions, but application in extensive grazing environments is challenging. A micrometeorological methodology for estimating herd-scale emissions using an indirect open-path spectroscopic technique and an atmospheric dispersion model is described. The methodology was deployed on five cattle properties across Queensland and Northern Territory, with measurements conducted during two occasions at one site. On each deployment, data were collected every 10 min for up to 7 h a day over 4 to 16 days. To increase the atmospheric concentration of CH 4 to measurable levels, cattle were confined to a known area around water points from~0800 to 1600 h, during which time measurements of wind statistics and line-averaged CH 4 concentration were taken. Filtering to remove erroneous data accounted for 35% of total observations. For five of the six deployments CH 4 emissions were within the expected range of 0.4 to 0.6 g/kg BW. At one site, emissions were~2 times expected values. There was small but consistent variation with time of day, although for some deployments measurements taken early in the day tended to be higher than at the other times. There was a weak linear relationship ( R 2 = 0.47) between animal BW and CH 4 emission per kg BW. Where it was possible to compare emissions in the early and late dry season at one site, it was speculated that higher emissions at the late dry season may have been attributed to poorer diet quality. It is concluded that the micrometeorological methodology using open-path lasers can be successfully deployed in extensive grazing conditions to directly measure CH 4 emissions from cattle at a herd scale.

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Section: Resultsmentioning

confidence: 99%

“…(Flesch et al, 2004 and. In these studies it was assumed that the area represented a uniform source of CH 4 ( Figure 2).…”

Section: Methodsmentioning

confidence: 99%

Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Tomkins

Charmley

2015

Animal

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“…The bLS technique uses the backward Lagrangian stochastic dispersion model for inversely calculating emissions from distributed sources [6]. The software Wintrax 2.0, a window-based bLS computer program developed by Thunder Beach Scientific [7] was used in this study.…”

Section: It Requires Knowledge Of the Tracer Concentration And Wind Fmentioning

confidence: 99%

Measuring Trace Gas Emission from Multi-Distributed Sources Using Vertical Radial Plume Mapping (VRPM) and Backward Lagrangian Stochastic (bLS) Techniques

Ro¹,

Johnson²,

Hunt³

et al. 2011

Atmosphere

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Two micrometeorological techniques for measuring trace gas emission rates from distributed area sources were evaluated using a variety of synthetic area sources. The vertical radial plume mapping (VRPM) and the backward Lagrangian stochastic (bLS) techniques with an open-path optical spectroscopic sensor were evaluated for relative accuracy for multiple emission-source and sensor configurations. The relative accuracy was calculated by dividing the measured emission rate by the actual emission rate; thus, a relative accuracy of 1.0 represents a perfect measure. For a single area emission source, the VRPM technique yielded a somewhat high relative accuracy of 1.38 ± 0.28. The bLS technique resulted in a relative accuracy close to unity, 0.98 ± 0.24. Relative accuracies for dual source emissions for the VRPM and bLS techniques were somewhat similar to single source emissions, 1.23 ± 0.17 and 0.94 ± 0.24, respectively. When the bLS technique was used with vertical point concentrations, the relative accuracy was unacceptably low, <0.62. However, when using multiple point sensors in a horizontal line, the bLS technique yielded a relative accuracy of 1.08 ± 0.44. Altogether, these results suggest that the bLS technique has significant potential for measuring trace gas emissions from distributed agricultural systems.

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“…The low 86% recovery of CH 4 was attributed to the presence of cattle (area source) confounding CH 4 point source release. Previous release and recovery work by Flesch et al (2004), using an open-path laser, found that the BLS recovered 102% of the controlled release. Harper et al (2010) looked at a number of release/ recovery BLS studies and concluded the BLS accuracy was 100 6 10%.…”

Section: Accuracy Of Micrometeorological Techniquesmentioning

confidence: 93%

Developments in micrometeorological methods for methane measurements

McGinn

2013

Animal

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Micrometeorological techniques can be applied to estimate methane (CH 4 ) emissions from ruminants and livestock manure using CH 4 concentration measured within the internal surface boundary layer. The main advantage of these techniques is that they are non-intrusive, thereby eliminating the impact of the measurement set-up on the calculated CH 4 emission. This review focuses on four micrometeorological techniques, namely, the integrated horizontal flux (IHF), flux gradient (FG), eddy covariance (EC) and the dispersion modelling using the backward Lagrangian stochastic method (BLS). Each technique has unique advantages and limitations when used for estimating enteric (ruminant) and manure CH 4 emissions. The IHF technique may be theoretically simpler then the FG, EC or BLS techniques, but all require high-resolution instruments to measure concentration. The EC and BLS techniques also require a measurement of the wind statistics. This review discusses the appropriate use of these four micrometeorological techniques for estimating CH 4 emissions in animal agriculture and the recent advances in measurement technology.Keywords: methane, micrometeorology, technique, livestock, manure ImplicationsAccurate measurements of methane (CH 4 ) emissions are essential to understand the importance of livestock's contribution to the greenhouse gas issue, and to develop mitigation strategies to improve the environmental sustainability of animal agriculture. These goals will become even more important as animal production escalates to meet global population demands. A clear understanding of the limitations and accuracy of measurement techniques presented in this review is needed to advance our understanding of CH 4 emissions from animal agriculture. IntroductionAnimal agriculture production is estimated to account for 8% to 10.8% of the global emissions of greenhouse gases (O'Mara, 2011). Methane (CH 4 ) is a large component of these emissions where globally the annual emission of ruminant enteric CH 4 is 91.9 million tonnes, and CH 4 from livestock manure is 11.2 million tonnes (O'Mara, 2011). The enteric CH 4 from ruminants alone is estimated to account for 25% to 40% of the anthropogenic release of CH 4 (Clark, 2013). It follows that accurate measurement of CH 4 emissions from ruminants and livestock manure is necessary to develop best management practices to reduce these CH 4 emissions and to ultimately improve the environmental sustainability of the livestock industry. These goals will become even more relevant with the expected expansion of the livestock industry because of increased demand for meat and milk by an escalating human population estimated to reach nine billion by 2050 (Smith et al., 2007). Fundamental to accurate measurement is the need for techniques that give direct measurements of CH 4 emissions under a variety of management and environmental conditions.A variety of CH 4 emission techniques for intensive livestock systems have been reviewed in the literature, for example, National Research Council (2003) a...

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Deducing Ground-to-Air Emissions from Observed Trace Gas Concentrations: A Field Trial

Cited by 306 publications

References 23 publications

Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Herd-scale measurements of methane emissions from cattle grazing extensive sub-tropical grasslands using the open-path laser technique

Measuring Trace Gas Emission from Multi-Distributed Sources Using Vertical Radial Plume Mapping (VRPM) and Backward Lagrangian Stochastic (bLS) Techniques

Developments in micrometeorological methods for methane measurements

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