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  1. Article ; Online: Laboratory Evaluation of the (355, 532) nm Particle Depolarization Ratio of Pure Pollen at 180.0° Lidar Backscattering Angle

    Danaël Cholleton / Patrick Rairoux / Alain Miffre

    Remote Sensing, Vol 14, Iss 3767, p

    2022  Volume 3767

    Abstract: While pollen is expected to impact public human health and the Earth’s climate more and more in the coming decades, lidar remote sensing of pollen has become an important developing research field. To differentiate among the pollen taxa, a polarization ... ...

    Abstract While pollen is expected to impact public human health and the Earth’s climate more and more in the coming decades, lidar remote sensing of pollen has become an important developing research field. To differentiate among the pollen taxa, a polarization lidar is an interesting tool since pollen exhibit non-spherical complex shapes. A key attribute is thus the lidar particle depolarization ratio ( PDR ) of pollen, which is however difficult to quantify as pollen are large and complex-shaped particles, far beyond the reach of light scattering numerical simulations. In this paper, a laboratory π-polarimeter is used to accurately evaluate the PDR of pure pollen, for the first time at the lidar exact backscattering angle of 180.0°. We hence reveal the lidar PDR of pure ragweed, ash, birch, pine, cypress and spruce pollens at 355 and 532 nm lidar wavelengths, as presented at the ELC 2021 conference. A striking result is the spectral dependence of the lidar PDR , highlighting the importance of dual-wavelength (or more) polarization lidars to identify pollen taxa. These spectral and polarimetric fingerprints of pure pollen, as they are accurate, can be used by the lidar community to invert multi-wavelength lidar polarization measurements involving pollen.
    Keywords lidar particle depolarization ratio ; pure pollen ; polarization lidar ; laboratory ; Science ; Q
    Subject code 333
    Language English
    Publishing date 2022-08-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Laboratory Evaluation of the (355, 532) nm Particle Depolarization Ratio of Pure Pollen at 180.0° Lidar Backscattering Angle

    Cholleton, Danaël / Rairoux, Patrick / Miffre, Alain

    Remote Sensing. 2022 Aug. 05, v. 14, no. 15

    2022  

    Abstract: While pollen is expected to impact public human health and the Earth’s climate more and more in the coming decades, lidar remote sensing of pollen has become an important developing research field. To differentiate among the pollen taxa, a polarization ... ...

    Abstract While pollen is expected to impact public human health and the Earth’s climate more and more in the coming decades, lidar remote sensing of pollen has become an important developing research field. To differentiate among the pollen taxa, a polarization lidar is an interesting tool since pollen exhibit non-spherical complex shapes. A key attribute is thus the lidar particle depolarization ratio (PDR) of pollen, which is however difficult to quantify as pollen are large and complex-shaped particles, far beyond the reach of light scattering numerical simulations. In this paper, a laboratory π-polarimeter is used to accurately evaluate the PDR of pure pollen, for the first time at the lidar exact backscattering angle of 180.0°. We hence reveal the lidar PDR of pure ragweed, ash, birch, pine, cypress and spruce pollens at 355 and 532 nm lidar wavelengths, as presented at the ELC 2021 conference. A striking result is the spectral dependence of the lidar PDR, highlighting the importance of dual-wavelength (or more) polarization lidars to identify pollen taxa. These spectral and polarimetric fingerprints of pure pollen, as they are accurate, can be used by the lidar community to invert multi-wavelength lidar polarization measurements involving pollen.
    Keywords Betula ; climate ; human health ; lidar ; polarimetry ; pollen
    Language English
    Dates of publication 2022-0805
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2513863-7
    ISSN 2072-4292
    ISSN 2072-4292
    DOI 10.3390/rs14153767
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: On the use of light polarization to investigate the size, shape, and refractive index dependence of backscattering Ångström exponents.

    Miffre, Alain / Cholleton, Danaël / Rairoux, Patrick

    Optics letters

    2020  Volume 45, Issue 5, Page(s) 1084–1087

    Abstract: In this Letter, we exploit the polarization property of light to investigate the Ångström exponent describing the wavelength dependence of optical backscatter between two wavelengths. Where previous interpretation of Ångström exponent was that of a ... ...

    Abstract In this Letter, we exploit the polarization property of light to investigate the Ångström exponent describing the wavelength dependence of optical backscatter between two wavelengths. Where previous interpretation of Ångström exponent was that of a particle size indicator, the use of light polarization makes it possible to investigate the Ångström exponent dependence on the particle shape by separately retrieving the backscattering Ångström exponent of the spherical (s) and non-spherical (ns) particles contained in an atmospheric particle mixture $(p) = \{s, {\rm ns}\}$(p)={s,ns}. As an output, analytical solutions of the Maxwell's equations (Lorenz-Mie theory, spheroidal model) can then be applied to investigate the Ångström exponent dependence on the particle size and complex refractive index for each assigned shape. Interestingly, lidar-retrieved vertical profiles of backscattering Ångström exponents specific to $s$s- and ns-particles can be used by the optical community to evaluate a range of involved particle sizes and complex refractive indices for both particle shapes, $s$s and ns, as we remotely demonstrate on a case study dedicated to a dust nucleation event.
    Language English
    Publishing date 2020-02-27
    Publishing country United States
    Document type Journal Article
    ISSN 1539-4794
    ISSN (online) 1539-4794
    DOI 10.1364/OL.385107
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Remote Sensing Observation of New Particle Formation Events with a (UV, VIS) Polarization Lidar

    Alain Miffre / Danaël Cholleton / Tahar Mehri / Patrick Rairoux

    Remote Sensing, Vol 11, Iss 15, p

    2019  Volume 1761

    Abstract: Observations of new particle formation events in free troposphere are rather seldom and limited in time and space, mainly due to the complexity and the cost of the required on-board instrumentation for airplane field campaigns. In this paper, a ... ...

    Abstract Observations of new particle formation events in free troposphere are rather seldom and limited in time and space, mainly due to the complexity and the cost of the required on-board instrumentation for airplane field campaigns. In this paper, a calibrated (UV, VIS) polarization elastic lidar (2β + 2δ) is used to remotely sense new particle formation events in the free troposphere in the presence of mineral dust particles. Using very efficient (UV, VIS) light polarization discriminators (1:10 7 ) and after robust calibration, the contribution of mineral dust particles to the co-polarized (UV, VIS) lidar channels could be removed, to reveal the backscattering coefficient of the newly nucleated particles after these numerous particles have grown to a size detectable with our lidar. Since our polarization and wavelength cross-talks are fully negligible, the observed variation in the (UV, VIS) particle backscattering time−altitude maps could be related to variations in the particle microphysics. Hence, day and nighttime differences, at low and high dust loadings, were observed in agreement with the observed nucleation process promoted by mineral dust. While light backscattering is more sensitive to small-sized particles at the UV lidar wavelength of 355 nm, such new particle formation events are here for the first time also remotely sensed at the VIS lidar wavelength of 532 nm at which most polarization lidars operate. Moreover, by addressing the (UV, VIS) backscattering Angstrom exponent, we could discuss the particles’ sizes addressed with our (UV, VIS) polarization lidar. As nucleation concerns the lowest modes of the particles’ size distribution, such a methodology may then be applied to reveal the lowest particle sizes that a (UV, VIS) polarization lidar can address, thus improving our understanding of the vertical and temporal extent of nucleation in free troposphere, where measurements are rather seldom.
    Keywords lidar ; polarization ; spectroscopy ; nucleation ; Angstrom exponent ; Science ; Q
    Subject code 333
    Language English
    Publishing date 2019-07-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  5. Article: Remote Sensing Observation of New Particle Formation Events with a (UV, VIS) Polarization Lidar

    Miffre, Alain / Cholleton, Danaël / Mehri, Tahar / Rairoux, Patrick

    Remote Sensing. 2019 July 26, v. 11, no. 15

    2019  

    Abstract: Observations of new particle formation events in free troposphere are rather seldom and limited in time and space, mainly due to the complexity and the cost of the required on-board instrumentation for airplane field campaigns. In this paper, a ... ...

    Abstract Observations of new particle formation events in free troposphere are rather seldom and limited in time and space, mainly due to the complexity and the cost of the required on-board instrumentation for airplane field campaigns. In this paper, a calibrated (UV, VIS) polarization elastic lidar (2β + 2δ) is used to remotely sense new particle formation events in the free troposphere in the presence of mineral dust particles. Using very efficient (UV, VIS) light polarization discriminators (1:107) and after robust calibration, the contribution of mineral dust particles to the co-polarized (UV, VIS) lidar channels could be removed, to reveal the backscattering coefficient of the newly nucleated particles after these numerous particles have grown to a size detectable with our lidar. Since our polarization and wavelength cross-talks are fully negligible, the observed variation in the (UV, VIS) particle backscattering time–altitude maps could be related to variations in the particle microphysics. Hence, day and nighttime differences, at low and high dust loadings, were observed in agreement with the observed nucleation process promoted by mineral dust. While light backscattering is more sensitive to small-sized particles at the UV lidar wavelength of 355 nm, such new particle formation events are here for the first time also remotely sensed at the VIS lidar wavelength of 532 nm at which most polarization lidars operate. Moreover, by addressing the (UV, VIS) backscattering Angstrom exponent, we could discuss the particles’ sizes addressed with our (UV, VIS) polarization lidar. As nucleation concerns the lowest modes of the particles’ size distribution, such a methodology may then be applied to reveal the lowest particle sizes that a (UV, VIS) polarization lidar can address, thus improving our understanding of the vertical and temporal extent of nucleation in free troposphere, where measurements are rather seldom.
    Keywords dust ; instrumentation ; lidar ; particle size ; phase transition ; polarized light ; remote sensing ; troposphere ; wavelengths
    Language English
    Dates of publication 2019-0726
    Publishing place Multidisciplinary Digital Publishing Institute
    Document type Article
    ZDB-ID 2513863-7
    ISSN 2072-4292
    ISSN 2072-4292
    DOI 10.3390/rs11151761
    Database NAL-Catalogue (AGRICOLA)

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  6. Article: Laboratory evaluation of the (VIS, IR) scattering matrix of complex-shaped ragweed pollen particles.

    Cholleton, Danaël / Bialic, Emilie / Dumas, Antoine / Kaluzny, Pascal / Rairoux, Patrick / Miffre, Alain

    Journal of quantitative spectroscopy & radiative transfer

    2020  Volume 254, Page(s) 107223

    Abstract: ... Ragweed ... ...

    Abstract Ragweed or
    Keywords covid19
    Language English
    Publishing date 2020-07-18
    Publishing country England
    Document type Journal Article
    ZDB-ID 1491916-3
    ISSN 1879-1352 ; 0022-4073
    ISSN (online) 1879-1352
    ISSN 0022-4073
    DOI 10.1016/j.jqsrt.2020.107223
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  7. Article: Laboratory evaluation of the (VIS, IR) scattering matrix of complex-shaped ragweed pollen particles

    Cholleton, Danaël Bialic / Emilie, Dumas / Antoine, Kaluzny / Pascal, Rairoux / Patrick, Miffre / Alain,

    Journal of Quantitative Spectroscopy and Radiative Transfer

    Abstract: Ragweed or Ambrosia artemisiifolia pollen is an important atmospheric constituent affecting the Earth's climate and public health The literature on light scattering by pollens embedded in ambient air is however rather sparse: polarization measurements ... ...

    Abstract Ragweed or Ambrosia artemisiifolia pollen is an important atmospheric constituent affecting the Earth's climate and public health The literature on light scattering by pollens embedded in ambient air is however rather sparse: polarization measurements are limited to the sole depolarization ratio and pollens are beyond the reach of numerically exact light scattering models mainly due to their tens of micrometre size Also, ragweed pollen presents a very complex shape, with a small-scale external structure exhibiting spikes that bears some resemblance with coronavirus, but also apertures and micrometre holes In this paper, to face such a complexity, a controlled-laboratory experiment is proposed to evaluate the scattering matrix of ragweed pollen embedded in ambient air It is based on a newly-built polarimeter, operating in the infra-red spectral range, to account for the large size of ragweed pollen Moreover, the ragweed scattering matrix is also evaluated in the visible spectral range to reveal the spectral dependence of the ragweed scattering matrix within experimental error bars As an output, precise spectral and polarimetric fingerprints for large size and complex-shaped ragweed pollen particles are then provided We believe our laboratory experiment may interest the light scattering community by complementing other light scattering experiments and proposing outlooks for numerical work on large and complex-shaped particles
    Keywords covid19
    Publisher WHO
    Document type Article
    Note WHO #Covidence: #652883
    Database COVID19

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