An Architecture Providing Depolarization Ratio Capability for a Multi-Wavelength Raman Lidar: Implementation and First Measurements

Rodríguez-Gómez, Alejandro; Sicard, Michaël; Granados-Muñoz, M. J.; Chahed, Enis Ben; Muñoz-Porcar, Constantino; Barragán, Rubén; Comerón, Adolfo; Rocadenbosch, Francesc; Vidal, Éric

doi:10.3390/s17122957

Cited by 10 publications

(11 citation statements)

References 55 publications

(81 reference statements)

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“…CommSensLab has developed a multiwavelength Raman lidar (a complete description is available in [ 22 ]), which has been recently upgraded with an auxiliary depolarization channel [ 18 ].…”

Section: Calibration and Estimation Of The Polarizer Anglementioning

confidence: 99%

“…The aerosol depolarization auxiliary channel [ 18 ] uses a separate telescope (a 70 mm aperture, 300 mm focal distance TAIR-3S telephoto lens, BelOMO, Minsk, Belarus). The rest of the optical setup includes a 1-mm field of view (FOV) stop iris (which provides an approximate FOV of 3.33 mrad), a polarization analyzer, an eye-piece lens, and an interference filter (Barr Associates, Inc., Westford, MA, USA), centered at 532 nm with a spectral width of 0.5 nm.…”

Section: Calibration and Estimation Of The Polarizer Anglementioning

confidence: 99%

“…We have presented recently [ 18 ] the implementation of a new architecture for a depolarization lidar. It is based on a two-telescope arrangement: the main telescope collects (among other returns) the elastically backscattered light at 532 nm, without any polarization discrimination; the auxiliary telescope collects only the depolarized component of the backscattered light at the same wavelength.…”

Section: Introductionmentioning

confidence: 99%

“…The estimation of the volume depolarization ratio [ 18 ], which is obtained from the comparison of the depolarization and total power channel outputs, can be corrected by considering that some amount of co-polar backscattered power is being detected because of the non-ideal position of the polarizer.…”

Section: Introductionmentioning

confidence: 99%

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Considerations about the Determination of the Depolarization Calibration Profile of a Two-Telescope Lidar and Its Implications for Volume Depolarization Ratio Retrieval

Comerón

Rodríguez-Gómez

Sicard

et al. 2018

Sensors

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We propose a new method for calculating the volume depolarization ratio of light backscattered by the atmosphere and a lidar system that employs an auxiliary telescope to detect the depolarized component. It takes into account the possible error in the positioning of the polarizer used in the auxiliary telescope. The theory of operation is presented and then applied to a few cases for which the actual position of the polarizer is estimated, and the improvement of the volume depolarization ratio in the molecular region is quantified. In comparison to the method used before, i.e., without correction, the agreement between the volume depolarization ratio with correction and the theoretical value in the molecular region is improved by a factor of 2–2.5.

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“…CommSensLab has developed a multiwavelength Raman lidar (a complete description is available in [ 22 ]), which has been recently upgraded with an auxiliary depolarization channel [ 18 ].…”

Section: Calibration and Estimation Of The Polarizer Anglementioning

confidence: 99%

Section: Calibration and Estimation Of The Polarizer Anglementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Considerations about the Determination of the Depolarization Calibration Profile of a Two-Telescope Lidar and Its Implications for Volume Depolarization Ratio Retrieval

Comerón

Rodríguez-Gómez

Sicard

et al. 2018

Sensors

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“…In this paper, we present simultaneous PRR and VRR measurements at 355 nm in order to evaluate the daytime/nighttime performances of both channels in different conditions of aerosol load. The European Aerosol Research Lidar Network/Universitat Politècnica de Catalunya (EARLINET/UPC) multi-wavelength lidar system [ 12 , 13 ] was modified for this purpose. An energy budget is presented in relative terms between both PRR and VRR channels and quantifies the gain in signal-to-noise ratio for day and nighttime operations.…”

Section: Introductionmentioning

confidence: 99%

A Comparative Analysis of Aerosol Optical Coefficients and Their Associated Errors Retrieved from Pure-Rotational and Vibro-Rotational Raman Lidar Signals

Zenteno-Hernández

Comerón

Rodríguez-Gómez

et al. 2021

Sensors

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This paper aims to quantify the improvement obtained with a purely rotational Raman (PRR) channel over a vibro-rotational Raman (VRR) channel, used in an aerosol lidar with elastic and Raman channels, in terms of signal-to-noise ratio (SNR), effective vertical resolution, and absolute and relative uncertainties associated to the retrieved aerosol optical (extinction and backscatter) coefficients. Measurements were made with the European Aerosol Research Lidar Network/Universitat Politècnica de Catalunya (EARLINET/UPC) multi-wavelength lidar system enabling a PRR channel at 353.9 nm, together with an already existing VRR (386.7 nm) and an elastic (354.7 nm) channels. Inversions were performed with the EARLINET Single Calculus Chain (SCC). When using PRR instead of VRR, the measurements show a gain in SNR of a factor 2.8 and about 7.6 for 3-h nighttime and daytime measurements, respectively. For 3-h nighttime (daytime) measurements the effective vertical resolution is reduced by 17% (20%), the absolute uncertainty (associated to the extinction) is divided by 2 (10) and the relative uncertainty is divided by 3 (7). During daytime, VRR extinction coefficient is retrieved in a limited height range (<2.2 km) preventing the SCC from finding a suitable calibration range in the search height range. So the advantage of using PRR instead of VRR is particularly evidenced in daytime conditions. For nighttime measurements, decreasing the time resolution from 3 to 1 h has nearly no effect on the relative performances of PRR vs. VRR.

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Ground/space, passive/active remote sensing observations coupled with particle dispersion modelling to understand the inter-continental transport of wildfire smoke plumes

Sicard

Granados-Muñoz

Alados-Arboledas

et al. 2019

Remote Sensing of Environment

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During the 2017 record-breaking burning season in Canada / United States, intense wild fires raged during the first week of September in the Pacific northwestern region (British Columbia, Alberta, Washington, Oregon, Idaho, Montana and northern California) burning mostly temperate coniferous forests. The heavy loads of smoke particles emitted in the atmosphere reached the Iberian Peninsula (IP) a few days later on 7 and 8 September. Satellite imagery allows to identify two main smoke clouds emitted during two different periods that were injected and transported in the atmosphere at several altitude levels. Columnar properties on 7 and 8 September at two Aerosol Robotic Network (AERONET) mid-altitude, background sites in northern and southern Spain are: aerosol optical depth (AOD) at 440 nm up to 0.62, Ångström exponent of 1.6-1.7, large dominance of small particles (fine mode fraction > 0.88), low absorption AOD at 440 nm (<0.008) and large single scattering albedo at 440 nm (>0.98). Profiles from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) show the presence of smoke particles in the stratosphere during the transport, whereas the smoke is only observed in the troposphere at its arrival over the IP. Portuguese and Spanish ground lidar stations from the European Aerosol Research Lidar Network / Aerosols, Clouds, and Trace gases Research InfraStructure Network (EARLINET/ACTRIS) and the Micro-Pulse Lidar NETwork (MPLNET) revealsmoke plumes with different properties: particle depolarization ratio and color ratio, respectively, of 0.05 and 2.5 in the mid troposphere (5 -9 km) and of 0.10 and 3.0 in the upper troposphere (10 -13 km). In the mid troposphere the particle depolarization ratio does not seem time-dependent during the transport whereas the color ratio seems to increase (larger particles sediment first). To analyze the horizontal and vertical transport of the smoke from its origin to the IP, particle dispersion modelling is performed with the Hybrid Single Particle Lagrangian Integrated Trajectory Model (HYSPLIT) parameterized with satellite-derived biomass burning emission estimates from the Global Fire Assimilation System (GFAS) of the Copernicus Atmosphere Monitoring Service (CAMS). Three compounds are simulated: carbon monoxide, black carbon and organic carbon. The results show that the first smoke plume which travels slowly reaches rapidly (~1 day) the upper troposphere and lower stratosphere (UTLS) but also shows evidence of large scale horizontal dispersion, while the second plume, entrained by strong subtropical jets, reaches the upper troposphere much slower (~2.5 days). Observations and dispersion modelling all together suggest that particle depolarization properties are enhanced during their vertical transport from the mid to the upper troposphere.Keywords. Time-space monitoring, ground-based and space-borne lidars, long-range transport of smoke plume, injection of particles up to the upper troposphere, particle dispersion model, smoke particle absorption and depolarization propert...

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An Architecture Providing Depolarization Ratio Capability for a Multi-Wavelength Raman Lidar: Implementation and First Measurements

Cited by 10 publications

References 55 publications

Considerations about the Determination of the Depolarization Calibration Profile of a Two-Telescope Lidar and Its Implications for Volume Depolarization Ratio Retrieval

Considerations about the Determination of the Depolarization Calibration Profile of a Two-Telescope Lidar and Its Implications for Volume Depolarization Ratio Retrieval

A Comparative Analysis of Aerosol Optical Coefficients and Their Associated Errors Retrieved from Pure-Rotational and Vibro-Rotational Raman Lidar Signals

Ground/space, passive/active remote sensing observations coupled with particle dispersion modelling to understand the inter-continental transport of wildfire smoke plumes

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