Greenhouse gas measurements over a 144 km open path in the Canary Islands

Brooke, James S. A.; Bernath, Peter F.; Kirchengast, Gottfried; Thomas, C. Barry; Wang, J.-G.; Tereszchuk, K.; Abad, G. González; Hargreaves, Robert J.; Beale, Christopher; Harrison, Jeremy J.; Schweitzer, S.; Proschek, V.; Martin, Philip A.; Kasyutich, Vasili L.; Gerbig, Christoph; Kolle, Olaf; Löscher, Armin

doi:10.5194/amt-5-2309-2012

Cited by 11 publications

(8 citation statements)

References 22 publications

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“…The first proof-of-concept experiment, which is described by Brooke et al (2012) (referred to as Betal2012 hereafter) and gives a technical overview of the ground-based experiment with preliminary results on CO 2 , was performed between La Palma and Tenerife in the Canary Islands in July 2011 (see Fig. 1).…”

Section: Introductionmentioning

confidence: 99%

Retrieval and validation of carbon dioxide, methane and water vapor for the Canary Islands IR-laser occultation experiment

et al. 2015

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Abstract. The first ground-based experiment to prove the concept of a novel space-based observation technique for microwave and infrared-laser occultation between low-Earthorbit satellites was performed in the Canary Islands between La Palma and Tenerife. For two nights from 21 to 22 July 2011 the experiment delivered the infrared-laser differential transmission principle for the measurement of greenhouse gases (GHGs) in the free atmosphere. Such global and long-term stable measurements of GHGs, accompanied also by measurements of thermodynamic parameters and line-of-sight wind in a self-calibrating way, have become very important for climate change monitoring. The experiment delivered promising initial data for demonstrating the new observation concept by retrieving volume mixing ratios of GHGs along a ∼ 144 km signal path at altitudes of ∼ 2.4 km. Here, we present a detailed analysis of the measurements, following a recent publication that introduced the experiment's technical setup and first results for an example retrieval of CO 2 . We present the observational and validation data sets, the latter simultaneously measured at the transmitter and receiver sites; the measurement data handling; and the differential transmission retrieval procedure. We also determine the individual and combined uncertainties influencing the results and present the retrieval results for 12 CO 2 , 13 CO 2 , C 18 OO, H 2 O and CH 4 . The new method is found to have a reliable basis for monitoring of greenhouse gases such as CO 2 , CH 4 , and H 2 O in the free atmosphere.

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Section: Introductionmentioning

confidence: 99%

Retrieval and validation of carbon dioxide, methane and water vapor for the Canary Islands IR-laser occultation experiment

et al. 2015

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“…wind speed (from LIO), jointly forming the LEO-LEO microwave and infrared laser occultation (LMIO) method .The retrieval of thermodynamic variables and greenhouse gases is well understood from a range of studies employing end-to-end simulations of the LMIO method. After the introduction of LMIO by Kirchengast and Schweitzer [2011] (linking for further details to the scientific reports by Kirchengast et al [2010] and Schweitzer [2010]), an up-to-date assessment of the LMO retrieval performance for thermodynamic profiles was provided by Schweitzer et al [2011a], a full LMIO clear-air retrieval performance assessment with focus on greenhouse gases was provided by Proschek et al [2011], an analysis of LIO signal propagation and signal-to-noise ratio aspects was provided by Schweitzer et al [2011b], and a study on LMIO greenhouse gas retrieval performance in cloudy air, accounting for scintillations from turbulence, was provided by Proschek et al [2014].An initial LIO ground demonstration experiment for greenhouse gas measurements over a 144 km cross-link at the Canary Islands was conducted as well [Brooke et al, 2012;Proschek et al, 2015] and needs for improved spectroscopic knowledge of target absorption lines for LIO laser signals were investigated [Harrison et al, 2011;Proschek et al, 2015].…”

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“…An initial LIO ground demonstration experiment for greenhouse gas measurements over a 144 km cross-link at the Canary Islands was conducted as well [Brooke et al, 2012;Proschek et al, 2015] and needs for improved spectroscopic knowledge of target absorption lines for LIO laser signals were investigated [Harrison et al, 2011;Proschek et al, 2015].…”

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An Abel transform for deriving line‐of‐sight wind profiles from LEO‐LEO infrared laser occultation measurements

Syndergaard

Kirchengast

2016

JGR Atmospheres

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We have developed a formula for the retrieval of the line‐of‐sight (l.o.s.) wind speed from future low Earth orbit (LEO) satellite‐to‐satellite infrared laser occultation measurements. The formula involves an Abelian integral transform akin to the Abel transform widely used for deriving refractive index from bending angle in Global Navigation Satellite System radio occultation measurements. Besides the Abelian integral transform, the formula is derived from a truncated series expansion of the volume absorption coefficient as a function of frequency and includes a simple absorption‐line‐asymmetry correction term. A first‐order formulation (referred to as the standard formula) is complemented by higher‐order terms that can be used for high‐accuracy computations. Under the assumptions of spherical symmetry and perfect knowledge of spectroscopy, the residual l.o.s. wind error from using the standard formula rather than the high‐accuracy formula is assessed to be small compared to that anticipated from measurement errors in a real experiment. Applying the new formula just in standard form to future infrared laser transmission profiles would therefore enable the retrieval of l.o.s. stratospheric wind profiles with an accuracy limited mainly by measurement errors, residual spectroscopic errors, and deviations from spherical symmetry.

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“…Xia et al (2008) demonstrated diode laser-based CH 4 detection at a minimum detection limit of 1.1 ppm m 21 with a 120-m optical pathlength but did not address in situ instrument drift. Brooke et al (2012) demonstrated 144-km openpath CO 2 measurements with ;4% accuracy across two mountaintops with a low-power diode laser-based occultation technique. Although they claimed the technique is easily extended to CH 4 measurements, the sensor was not calibrated in situ and long-term stability of the retrievals was not quantified.…”

Section: Introductionmentioning

confidence: 99%

Long-Path Quantum Cascade Laser–Based Sensor for Methane Measurements

Michel

Miller

Sun

et al. 2016

Journal of Atmospheric and Oceanic Technology

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A long-path methane (CH 4 ) sensor was developed and field deployed using an 8-mm quantum cascade laser. The high optical power (40 mW) of the laser allowed for path-integrated measurements of ambient CH 4 at total pathlengths from 100 to 1200 m with the use of a retroreflector. Wavelength modulation spectroscopy was used to make high-precision measurements of atmospheric pressure-broadened CH 4 absorption over these long distances. An in-line reference cell with higher harmonic detection provided metrics of system stability in rapidly changing and harsh environments. The system consumed less than 100 W of power and required no consumables. The measurements intercompared favorably (typically less than 5% difference) with a commercial in situ methane sensor when accounting for the different spatiotemporal scales of the measurements. The sensor was field deployed for 2 weeks at an arctic lake to examine the robustness of the approach in harsh field environments. Shortterm precision over a 458-m pathlength was 10 ppbv at 1 Hz, equivalent to a signal from a methane enhancement above background of 5 ppmv in a 1-m length. The sensor performed well in a range of harsh environmental conditions, including snow, rain, wind, and changing temperatures. These field measurements demonstrate the capabilities of the approach for use in detecting large but highly variable emissions in arctic environments.

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Greenhouse gas measurements over a 144 km open path in the Canary Islands

Cited by 11 publications

References 22 publications

Retrieval and validation of carbon dioxide, methane and water vapor for the Canary Islands IR-laser occultation experiment

Retrieval and validation of carbon dioxide, methane and water vapor for the Canary Islands IR-laser occultation experiment

An Abel transform for deriving line‐of‐sight wind profiles from LEO‐LEO infrared laser occultation measurements

Long-Path Quantum Cascade Laser–Based Sensor for Methane Measurements

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