Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurements
We apply a two-way transmittance constraint to nighttime CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations of volcanic aerosol layers to retrieve estimates of the particulate lidar ratio (<i>S</i><sub>p</sub>) at 532 nm. This technique is applied to th...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2017-07-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | https://www.atmos-chem-phys.net/17/8599/2017/acp-17-8599-2017.pdf |
| _version_ | 1819238972130328576 |
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| author | A. T. Prata S. A. Young S. T. Siems M. J. Manton |
| author_facet | A. T. Prata S. A. Young S. T. Siems M. J. Manton |
| author_sort | A. T. Prata |
| collection | DOAJ |
| description | We apply a two-way transmittance constraint to nighttime CALIOP
(Cloud-Aerosol Lidar with Orthogonal Polarization) observations of volcanic
aerosol layers to retrieve estimates of the particulate lidar ratio
(<i>S</i><sub>p</sub>) at 532 nm. This technique is applied to three
volcanic eruption case studies that were found to have injected aerosols
directly into the stratosphere. Numerous lidar observations permitted
characterization of the optical and geometric properties of the volcanic
aerosol layers over a time period of 1–2 weeks. For the volcanic ash-rich
layers produced by the Puyehue-Cordón Caulle eruption (June 2011), we obtain
mean and median particulate lidar ratios of 69 ± 13 sr and
67 sr, respectively. For the sulfate-rich aerosol layers produced by
Kasatochi (August 2008) and Sarychev Peak (June 2009), the means of the
retrieved lidar ratios were 66 ± 19 sr (median 60 sr)
and 63 ± 14 sr (median 59 sr), respectively. The 532 nm
layer-integrated particulate depolarization ratios (<i>δ</i><sub>p</sub>)
observed for the Puyehue layers (<i>δ</i><sub>p</sub> = 0.33 ± 0.03)
were much larger than those found for the volcanic aerosol layers produced by
the Kasatochi (<i>δ</i><sub>p</sub> = 0.09 ± 0.03) and Sarychev
(<i>δ</i><sub>p</sub> = 0.05 ± 0.04) eruptions. However, for the
Sarychev layers we observe an exponential decay (<i>e</i>-folding time of
3.6 days) in <i>δ</i><sub>p</sub> with time from 0.27 to 0.03. Similar
decreases in the layer-integrated attenuated colour ratios with time were
observed for the Sarychev case. In general, the Puyehue layers exhibited
larger colour ratios (<i>χ</i>′ = 0.53 ± 0.07) than what was
observed for the Kasatochi (<i>χ</i>′ = 0.35 ± 0.07) and Sarychev
(<i>χ</i>′ = 0.32 ± 0.07) layers, indicating that the Puyehue
layers were generally composed of larger particles. These observations are
particularly relevant to the new stratospheric aerosol subtyping
classification scheme, which has been incorporated into version 4 of the
level 2 CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data products. |
| first_indexed | 2024-12-23T13:44:43Z |
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| id | doaj.art-5e7903a832bc4dcbb1dd395ae210e129 |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-23T13:44:43Z |
| publishDate | 2017-07-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-5e7903a832bc4dcbb1dd395ae210e1292022-12-21T17:44:45ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242017-07-01178599861810.5194/acp-17-8599-2017Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurementsA. T. Prata0S. A. Young1S. T. Siems2M. J. Manton3School of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, AustraliaCSIRO Oceans and Atmosphere, Aspendale, Victoria 3195, AustraliaSchool of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, AustraliaSchool of Earth, Atmosphere and Environment, Monash University, Clayton, Victoria 3800, AustraliaWe apply a two-way transmittance constraint to nighttime CALIOP (Cloud-Aerosol Lidar with Orthogonal Polarization) observations of volcanic aerosol layers to retrieve estimates of the particulate lidar ratio (<i>S</i><sub>p</sub>) at 532 nm. This technique is applied to three volcanic eruption case studies that were found to have injected aerosols directly into the stratosphere. Numerous lidar observations permitted characterization of the optical and geometric properties of the volcanic aerosol layers over a time period of 1–2 weeks. For the volcanic ash-rich layers produced by the Puyehue-Cordón Caulle eruption (June 2011), we obtain mean and median particulate lidar ratios of 69 ± 13 sr and 67 sr, respectively. For the sulfate-rich aerosol layers produced by Kasatochi (August 2008) and Sarychev Peak (June 2009), the means of the retrieved lidar ratios were 66 ± 19 sr (median 60 sr) and 63 ± 14 sr (median 59 sr), respectively. The 532 nm layer-integrated particulate depolarization ratios (<i>δ</i><sub>p</sub>) observed for the Puyehue layers (<i>δ</i><sub>p</sub> = 0.33 ± 0.03) were much larger than those found for the volcanic aerosol layers produced by the Kasatochi (<i>δ</i><sub>p</sub> = 0.09 ± 0.03) and Sarychev (<i>δ</i><sub>p</sub> = 0.05 ± 0.04) eruptions. However, for the Sarychev layers we observe an exponential decay (<i>e</i>-folding time of 3.6 days) in <i>δ</i><sub>p</sub> with time from 0.27 to 0.03. Similar decreases in the layer-integrated attenuated colour ratios with time were observed for the Sarychev case. In general, the Puyehue layers exhibited larger colour ratios (<i>χ</i>′ = 0.53 ± 0.07) than what was observed for the Kasatochi (<i>χ</i>′ = 0.35 ± 0.07) and Sarychev (<i>χ</i>′ = 0.32 ± 0.07) layers, indicating that the Puyehue layers were generally composed of larger particles. These observations are particularly relevant to the new stratospheric aerosol subtyping classification scheme, which has been incorporated into version 4 of the level 2 CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) data products.https://www.atmos-chem-phys.net/17/8599/2017/acp-17-8599-2017.pdf |
| spellingShingle | A. T. Prata S. A. Young S. T. Siems M. J. Manton Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurements Atmospheric Chemistry and Physics |
| title | Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurements |
| title_full | Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurements |
| title_fullStr | Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurements |
| title_full_unstemmed | Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurements |
| title_short | Lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from CALIOP measurements |
| title_sort | lidar ratios of stratospheric volcanic ash and sulfate aerosols retrieved from caliop measurements |
| url | https://www.atmos-chem-phys.net/17/8599/2017/acp-17-8599-2017.pdf |
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