Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval
International audience Abstract In this paper, accurate UV polarization measurements are performed on a volcanic ash cloud after long-range transport at Lyon, France (45.76°N, 4.83°E). The volcanic particles are released from the mid-April 2010 eruption of the Eyjafjallajökull Icelandic volcano (63....
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Online Access: | https://hal.science/hal-04452147 https://doi.org/10.1175/JTECH-D-11-00124.1 |
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ftunivlyon:oai:HAL:hal-04452147v1 2024-09-09T19:39:37+00:00 Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval Miffre, Alain David, G. Thomas, B. Chacra, M. Abou Rairoux, P. Laboratoire de Spectrométrie Ionique et Moléculaire (LASIM) Université Claude Bernard Lyon 1 (UCBL) Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS) 2012-04-01 https://hal.science/hal-04452147 https://doi.org/10.1175/JTECH-D-11-00124.1 en eng HAL CCSD American Meteorological Society info:eu-repo/semantics/altIdentifier/doi/10.1175/JTECH-D-11-00124.1 hal-04452147 https://hal.science/hal-04452147 doi:10.1175/JTECH-D-11-00124.1 ISSN: 0739-0572 EISSN: 1520-0426 Journal of Atmospheric and Oceanic Technology https://hal.science/hal-04452147 Journal of Atmospheric and Oceanic Technology, 2012, 29 (4), pp.558-568. ⟨10.1175/JTECH-D-11-00124.1⟩ [PHYS.PHYS]Physics [physics]/Physics [physics] info:eu-repo/semantics/article Journal articles 2012 ftunivlyon https://doi.org/10.1175/JTECH-D-11-00124.1 2024-08-02T05:11:15Z International audience Abstract In this paper, accurate UV polarization measurements are performed on a volcanic ash cloud after long-range transport at Lyon, France (45.76°N, 4.83°E). The volcanic particles are released from the mid-April 2010 eruption of the Eyjafjallajökull Icelandic volcano (63.63°N, 19.62°W). The aerosol UV depolarization, which arises from nonspherical volcanic ash particles, serves as an independent means to discriminate ash from nonash particles in the volcanic cloud. This discrimination is only feasible if the intrinsic ash particle depolarization ration δash is accurately determined. In this paper, the δash value [δash = (40.5 ± 2.0)%] is derived from literature laboratory measurements on a scattering matrix to ensure ash particle specificity. It is shown that traditional approaches, based on direct lidar depolarization ratio δa measurements, are only valid very close to the source region, because δa may be very different from δash, when nonash particles are present. For the first time, observed lidar depolarization ratios, in the range from a few percent to 40%, are hence interpreted in comparison with δash taken as a reference. It is then shown how to use the sensitive and accurate UV polarization measurements to access to the size-averaged number concentration vertical profile of volcanic ash particles in the troposphere. Vertical profiles of the backscattering coefficient specific to volcanic ash particles, providing altitude-resolved ash particle number concentrations, are presented in the troposphere after optical scattering computation. This new methodology can be applied to other aerosols events and for other optical remote sensing experiments. Article in Journal/Newspaper Eyjafjallajökull Université de Lyon: HAL Journal of Atmospheric and Oceanic Technology 29 4 558 568 |
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Open Polar |
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Université de Lyon: HAL |
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ftunivlyon |
language |
English |
topic |
[PHYS.PHYS]Physics [physics]/Physics [physics] |
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[PHYS.PHYS]Physics [physics]/Physics [physics] Miffre, Alain David, G. Thomas, B. Chacra, M. Abou Rairoux, P. Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval |
topic_facet |
[PHYS.PHYS]Physics [physics]/Physics [physics] |
description |
International audience Abstract In this paper, accurate UV polarization measurements are performed on a volcanic ash cloud after long-range transport at Lyon, France (45.76°N, 4.83°E). The volcanic particles are released from the mid-April 2010 eruption of the Eyjafjallajökull Icelandic volcano (63.63°N, 19.62°W). The aerosol UV depolarization, which arises from nonspherical volcanic ash particles, serves as an independent means to discriminate ash from nonash particles in the volcanic cloud. This discrimination is only feasible if the intrinsic ash particle depolarization ration δash is accurately determined. In this paper, the δash value [δash = (40.5 ± 2.0)%] is derived from literature laboratory measurements on a scattering matrix to ensure ash particle specificity. It is shown that traditional approaches, based on direct lidar depolarization ratio δa measurements, are only valid very close to the source region, because δa may be very different from δash, when nonash particles are present. For the first time, observed lidar depolarization ratios, in the range from a few percent to 40%, are hence interpreted in comparison with δash taken as a reference. It is then shown how to use the sensitive and accurate UV polarization measurements to access to the size-averaged number concentration vertical profile of volcanic ash particles in the troposphere. Vertical profiles of the backscattering coefficient specific to volcanic ash particles, providing altitude-resolved ash particle number concentrations, are presented in the troposphere after optical scattering computation. This new methodology can be applied to other aerosols events and for other optical remote sensing experiments. |
author2 |
Laboratoire de Spectrométrie Ionique et Moléculaire (LASIM) Université Claude Bernard Lyon 1 (UCBL) Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS) |
format |
Article in Journal/Newspaper |
author |
Miffre, Alain David, G. Thomas, B. Chacra, M. Abou Rairoux, P. |
author_facet |
Miffre, Alain David, G. Thomas, B. Chacra, M. Abou Rairoux, P. |
author_sort |
Miffre, Alain |
title |
Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval |
title_short |
Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval |
title_full |
Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval |
title_fullStr |
Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval |
title_full_unstemmed |
Interpretation of Accurate UV Polarization Lidar Measurements: Application to Volcanic Ash Number Concentration Retrieval |
title_sort |
interpretation of accurate uv polarization lidar measurements: application to volcanic ash number concentration retrieval |
publisher |
HAL CCSD |
publishDate |
2012 |
url |
https://hal.science/hal-04452147 https://doi.org/10.1175/JTECH-D-11-00124.1 |
genre |
Eyjafjallajökull |
genre_facet |
Eyjafjallajökull |
op_source |
ISSN: 0739-0572 EISSN: 1520-0426 Journal of Atmospheric and Oceanic Technology https://hal.science/hal-04452147 Journal of Atmospheric and Oceanic Technology, 2012, 29 (4), pp.558-568. ⟨10.1175/JTECH-D-11-00124.1⟩ |
op_relation |
info:eu-repo/semantics/altIdentifier/doi/10.1175/JTECH-D-11-00124.1 hal-04452147 https://hal.science/hal-04452147 doi:10.1175/JTECH-D-11-00124.1 |
op_doi |
https://doi.org/10.1175/JTECH-D-11-00124.1 |
container_title |
Journal of Atmospheric and Oceanic Technology |
container_volume |
29 |
container_issue |
4 |
container_start_page |
558 |
op_container_end_page |
568 |
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1809908729640910848 |