Laser Spectroscopy for Atmospheric and Environmental Sensing

Fiddler, Marc N.; Begashaw, Israel; Mickens, Matthew A.; Collingwood, Michael S.; Assefa, Zerihun; Bililign, Solomon

doi:10.3390/s91210447

Cited by 95 publications

(51 citation statements)

References 400 publications

(364 reference statements)

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“…These features make MEDEE suitable for measurements of different trace gases and compatible with a wide array of analysers. For example, the quantum cascade laser absorption spectrometer (QCLAS) (Joly et al, 2011) or the cavity ringdown spectrometer (CDRS) (Crosson, 2008;Langridge et al, 2008;Fiddler et al, 2009), which monitor trace gases such as CO, CH 4 , N 2 O or NO x .…”

Section: Discussionmentioning

confidence: 99%

A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO2 and H2O fluxes

Baghi¹,

Durand²,

Jambert³

et al. 2012

Atmos. Meas. Tech.

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Abstract. The disjunct eddy covariance (DEC) method is an interesting alternative to the conventional eddy covariance (EC) method because it allows the estimation of turbulent fluxes of species for which fast sensors are not available. We have developed and validated a new disjunct sampling system (called MEDEE). This system is built with chemically inert materials. Air samples are taken quickly and alternately in two cylindrical reservoirs, the internal pressures of which are regulated by a moving piston. The MEDEE system was designed to be operated either on the ground or aboard an aircraft. It is also compatible with most analysers since it transfers the air samples at a regulated pressure. To validate the system, DEC and EC measurements of CO 2 and latent heat fluxes were performed concurrently during a field campaign. EC fluxes were first compared to simulated DEC (SDEC) fluxes and then to actual DEC fluxes.Both the simulated and actual DEC fluxes showed a good agreement with EC fluxes in terms of correlation. The determination coefficients (R 2 ) were 0.93 and 0.91 for DEC and SDEC latent heat fluxes, respectively. For DEC and SDEC CO 2 fluxes R 2 was 0.69 in both cases. The conditions of low fluxes experienced during the campaign impaired the comparison of the different techniques especially for CO 2 flux measurements. Linear regression analysis showed an 14 % underestimation of DEC fluxes for both CO 2 and latent heat compared to EC fluxes.A first field campaign, focusing on biogenic volatile organic compound (BVOC) emissions, was carried out to measure isoprene fluxes above a downy oak (Quercus Pubescens) forest in the south-east of France. The measured standard emission rate was in the lower range of reported values in earlier studies. Further analysis will be conducted through ground-based and airborne campaigns in the coming years.

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Section: Discussionmentioning

confidence: 99%

A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO2 and H2O fluxes

Baghi¹,

Durand²,

Jambert³

et al. 2012

Atmos. Meas. Tech.

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“…This procedure can improve the measurement precision. Therefore, WMS has proven to be an excellent tool for trace gas detection in environmental [13][14][15], biomedical [16][17][18], industrial [19,20] and national security [15] applications. WMS requires a tunable laser capable of single-frequency emission and a narrow linewidth at the targeted absorption line of a gas molecule.…”

Section: Introductionmentioning

confidence: 99%

Ppb-level mid-infrared ethane detection based on three measurement schemes using a 3.34-μm continuous-wave interband cascade laser

Zheng

et al. 2016

Appl. Phys. B

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For the quasi-simultaneous DAS and WMS scheme, both the 2f signal and the direct absorption signal were simultaneously extracted using a LabVIEW platform, and four C 2 H 6 samples (0, 30, 60 and 90 ppbv with nitrogen as the balance gas) were used as the target gases to assess the sensor performance. A detailed comparison of the three measurement schemes is reported. Atmospheric C 2 H 6 measurements on the Rice University campus and a field test at a compressed natural gas station in Houston, TX, were conducted to evaluate the performance of the sensor system as a robust and reliable field-deployable sensor system.

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“…As early as 1983, Filho et al (1983) measured the scintillation spectra of a microwave propagating over a distance of 4.1 km in central London (Filho et al, 1983). The frequency of the microwave used was off resonance from the 60 GHz oxygen absorption peak, and the wavelength (5.4 mm) was much larger than the size of aerosol particles.…”

Section: Introductionmentioning

confidence: 99%

“…2 Methodology based on theoretical analysis 2.1 Relationship between log-intensity variance and the imaginary part of the ARISP For a planar or spherical wave in a slowly varying turbulence field, the two-dimensional log-intensity spectrum is (Filho et al, 1983)…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, n is the spectrum of the refractive index, where the subscript n denotes the refractive index, the subscripts Re and Im denote the real and the imaginary parts of the refractive index, respectively, and the subscript IR denotes the correlation between the real and imaginary parts. In the following analysis, it is assumed that the fluctuations in the real and imaginary parts of the refractive index are not correlated (Filho et al, 1983); therefore, the joint term can be neglected. In the atmospheric window wave used for propagation, the absorption contribution is due to aerosols.…”

Section: Introductionmentioning

confidence: 99%

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A new method for measuring the imaginary part of the atmospheric refractive index structure parameter in the urban surface layer

et al. 2015

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Abstract. The atmospheric refractive index consists of both real and imaginary parts. The intensity of refractive index fluctuations is generally expressed as the refractive index structure parameter, with the real part reflecting the strength of atmospheric turbulence and the imaginary part reflecting absorption in the light path. A large aperture scintillometer (LAS) is often used to measure the structure parameter of the real part of the atmospheric refractive index, from which the sensible and latent heat fluxes can further be obtained, whereas the influence of the imaginary part is ignored or considered noise. In this theoretical analysis study, the relationship between logarithmic light intensity variance and the atmospheric refractive index structure parameter (ARISP), as well as that between the logarithmic light intensity structure function and the ARISP, is derived. Additionally, a simple expression for the imaginary part of the ARISP is obtained which can be conveniently used to determine the imaginary part of the ARISP from LAS measurements. Moreover, these relationships provide a new method for estimating the outer scale of turbulence. Light propagation experiments were performed in the urban surface layer, from which the imaginary part of the ARISP was calculated. The experimental results showed good agreement with the presented theory. The results also suggest that the imaginary part of the ARISP exhibits a different diurnal variation from that of the real part. For the wavelength of light used (0.62 µm), the variation of the imaginary part of the ARISP is related to both the turbulent transport process and the spatial distribution characteristics of aerosols.

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Laser Spectroscopy for Atmospheric and Environmental Sensing

Cited by 95 publications

References 400 publications

A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO<sub>2</sub> and H<sub>2</sub>O fluxes

A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO<sub>2</sub> and H<sub>2</sub>O fluxes

Ppb-level mid-infrared ethane detection based on three measurement schemes using a 3.34-μm continuous-wave interband cascade laser

A new method for measuring the imaginary part of the atmospheric refractive index structure parameter in the urban surface layer

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Laser Spectroscopy for Atmospheric and Environmental Sensing

Cited by 95 publications

References 400 publications

A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O fluxes

A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO&lt;sub&gt;2&lt;/sub&gt; and H&lt;sub&gt;2&lt;/sub&gt;O fluxes

Ppb-level mid-infrared ethane detection based on three measurement schemes using a 3.34-μm continuous-wave interband cascade laser

A new method for measuring the imaginary part of the atmospheric refractive index structure parameter in the urban surface layer

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A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO<sub>2</sub> and H<sub>2</sub>O fluxes

A new disjunct eddy-covariance system for BVOC flux measurements – validation on CO<sub>2</sub> and H<sub>2</sub>O fluxes