Open-path dual-comb spectroscopy to an airborne retroreflector

Cossel, Kevin C.; Waxman, E.; Giorgetta, Fabrizio R.; Cermak, Michael; Coddington, Ian; Hesselius, Daniel; Ruben, S Luis; Swann, William C.; Truong, Gar-Wing; Rieker, Gregory B.; Newbury, Nathan R.

doi:10.1364/optica.4.000724

Cited by 95 publications

(57 citation statements)

References 30 publications

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“…One of the primary advantages of UAVs is that they are uniquely suited to characterizing methane plumes in three dimensions while flying in close proximity to the source, improving confidence in attribution. To date, various attempts have been made to measure methane from a UAV (Khan et al 2012, Brownlow et al 2016, Barchyn et al 2017, Cossel et al 2017, Emran et al 2017, Smith et al 2017. The first comprehensive study investigating UAV methanesensing potential focused on a single compressor station, which was monitored over a one-week period by a fixed-wing UAV (Nathan et al 2015).…”

Section: Unmanned Aerial Vehiclesmentioning

confidence: 99%

A review of close-range and screening technologies for mitigating fugitive methane emissions in upstream oil and gas

Fox

Barchyn

Risk

et al. 2019

Environ. Res. Lett.

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Fugitive methane emissions from the oil and gas industry are targeted using leak detection and repair (LDAR) programs. Until recently, only a limited number of measurement standards have been permitted by most regulators, with emphasis on close-range methods (e.g. Method-21, optical gas imaging). Although close-range methods are essential for source identification, they can be labor-intensive. To improve LDAR efficiency, there has been a policy shift in Canada and the United States towards incorporating alternative technologies. However, the suitability of these technologies for LDAR remains unclear. In this paper, we systematically review and compare six technology classes for use in LDAR: handheld instruments, fixed sensors, mobile ground labs (MGLs), unmanned aerial vehicles (UAVs), aircraft, and satellites. These technologies encompass broad spatial and temporal scales of measurement. Minimum detection limits for technology classes range from <1 g h−1 for Method 21 instruments to 7.1 × 106 g h−1 for the GOSAT satellite, and uncertainties are poorly constrained. To leverage the diverse capabilities of these technologies, we introduce a hybrid screening-confirmation approach to LDAR called a comprehensive monitoring program. Here, a screening technology is used to rapidly tag high-emitting sites to direct close-range source identification. Currently, fixed sensors, MGLs, UAVs, and aircraft could be used as screening technologies, but their performances must be evaluated under a range of environmental and operational conditions to better constrain detection effectiveness. Methane-sensing satellites are improving rapidly and may soon be ready for facility-scale screening. We conclude with a speculative discussion of the future of LDAR, touching on integration, analytics, incentivization, and regulatory pathways.

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Section: Unmanned Aerial Vehiclesmentioning

confidence: 99%

A review of close-range and screening technologies for mitigating fugitive methane emissions in upstream oil and gas

Fox

Barchyn

Risk

et al. 2019

Environ. Res. Lett.

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“…We then servo the overall telescope pointing via its gimbal using the LED spot location on the camera. Further servo details are described in Cossel et al (2017). Figure 3b shows the return power for both systems as a function of time.…”

Section: Launch-receive Telescopementioning

confidence: 99%

Intercomparison of open-path trace gas measurements with two dual-frequency-comb spectrometers

et al. 2017

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Abstract. We present the first quantitative intercomparison between two open-path dual-comb spectroscopy (DCS) instruments which were operated across adjacent 2 km openair paths over a 2-week period. We used DCS to measure the atmospheric absorption spectrum in the near infrared from 6023 to 6376 cm −1 (1568 to 1660 nm), corresponding to a 355 cm −1 bandwidth, at 0.0067 cm −1 sample spacing. The measured absorption spectra agree with each other to within 5 × 10 −4 in absorbance without any external calibration of either instrument. The absorption spectra are fit to retrieve path-integrated concentrations for carbon dioxide (CO 2 ), methane (CH 4 ), water (H 2 O), and deuterated water (HDO). The retrieved dry mole fractions agree to 0.14 % (0.57 ppm) for CO 2 , 0.35 % (7 ppb) for CH 4 , and 0.40 % (36 ppm) for H 2 O at ∼ 30 s integration time over the 2-week measurement campaign, which included 24 • C outdoor temperature variations and periods of strong atmospheric turbulence. This agreement is at least an order of magnitude better than conventional active-source open-path instrument intercomparisons and is particularly relevant to future regional flux measurements as it allows accurate comparisons of open-path DCS data across locations and time. We additionally compare the open-path DCS retrievals to a World Meteorological Organization (WMO)-calibrated cavity ring-down point sensor located along the path with good agreement. Shortterm and long-term differences between the open-path DCS and point sensor are attributed, respectively, to spatial sampling discrepancies and to inaccuracies in the current spectral database used to fit the DCS data. Finally, the 2-week measurement campaign yields diurnal cycles of CO 2 and CH 4 that are consistent with the presence of local sources of CO 2 and absence of local sources of CH 4 .

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“…Solutions for remote comparisons that reach 10 −18 firstly without optical fiber link and secondly over intercontinental distances are still missing. For the former, free-space optical links studied in [196] [197] [198] [199] could be extended to a few 100 km distances with the help of an airborne platform.…”

Section: Chronometric Geodesymentioning

confidence: 99%

The unit of time: Present and future directions

Bize

2019

Comptes Rendus. Physique

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Some 50 years ago, physicists, and after them the entire world, started to found their time reference on atomic properties instead of motions of the Earth that have been in use since the origin. Far from being an arrival point, this decision marked the beginning of an adventure characterized by a 6 orders of magnitude improvement in the uncertainty of realization of atomic frequency and time references. Ever progressing atomic frequency standards and time references derived from them are key resources for science and for society. We will describe how the unit of time is realized with a fractional accuracy approaching 10 −16 and how it is delivered to users via the elaboration of the international atomic time. We will describe the tremendous progress of optical frequency metrology over the last 20 years which led to a novel generation of optical frequency standards with fractional uncertainties of 10 −18 . We will describe work toward a possible redefinition of the SI second based on such standards. We will describe existing and emerging applications of atomic frequency standards in science.

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Open-path dual-comb spectroscopy to an airborne retroreflector

Cited by 95 publications

References 30 publications

A review of close-range and screening technologies for mitigating fugitive methane emissions in upstream oil and gas

A review of close-range and screening technologies for mitigating fugitive methane emissions in upstream oil and gas

Intercomparison of open-path trace gas measurements with two dual-frequency-comb spectrometers

The unit of time: Present and future directions

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