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Lidar depolarization measurement of fresh volcanic ash from Mt. Etna, Italy
Author(s)
Language
English
Obiettivo Specifico
3.6. Fisica del vulcanismo
Status
Published
JCR Journal
JCR Journal
Title of the book
Issue/vol(year)
/62 (2012)
Pages (printed)
34-40
Issued date
August 8, 2012
Keywords
Abstract
A small, portable, polarization lidar system with scanning capability was used to perform range resolved
measurements of fresh erupted volcanic plume from Mount Etna in Italy. Measurements were carried out
on November 15, 2010 during a volcanic plume emission event by placing the lidar very close to volcano
summit craters. Depolarization measurements highlighted that aerosol of different shape and optical
properties were emitted by the two involved vents, Bocca Nuova and North-East Craters. In the plume
emitted from Bocca Nuova Crater the mean value of aerosol linear depolarization ratio resulted near to
zero, corresponding to non depolarizing particles or liquid droplets, while values of (16 2)% and
(45 3)% were observed in the ash plume emitted from North-East Crater, in the morning and in the
afternoon, respectively. The retrieved values of volcanic aerosol depolarization ratio, aerosol backscattering
and lidar-ratio allowed distinguishing the changes in the properties of the emitted aerosol.
Furthermore, the ash mass concentration at source was estimated, reaching a maximum value of
24,000 6000 mg m 3, with an additional systematic uncertainty of 50% related to the assumption of an
effective radius of 10 mm for ash particles
measurements of fresh erupted volcanic plume from Mount Etna in Italy. Measurements were carried out
on November 15, 2010 during a volcanic plume emission event by placing the lidar very close to volcano
summit craters. Depolarization measurements highlighted that aerosol of different shape and optical
properties were emitted by the two involved vents, Bocca Nuova and North-East Craters. In the plume
emitted from Bocca Nuova Crater the mean value of aerosol linear depolarization ratio resulted near to
zero, corresponding to non depolarizing particles or liquid droplets, while values of (16 2)% and
(45 3)% were observed in the ash plume emitted from North-East Crater, in the morning and in the
afternoon, respectively. The retrieved values of volcanic aerosol depolarization ratio, aerosol backscattering
and lidar-ratio allowed distinguishing the changes in the properties of the emitted aerosol.
Furthermore, the ash mass concentration at source was estimated, reaching a maximum value of
24,000 6000 mg m 3, with an additional systematic uncertainty of 50% related to the assumption of an
effective radius of 10 mm for ash particles
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