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| Titel |
Observations of the spectral dependence of linear particle depolarization ratio of aerosols using NASA Langley airborne High Spectral Resolution Lidar |
| VerfasserIn |
S. P. Burton, J. W. Hair, M. Kahnert, R. A. Ferrare, C. A. Hostetler, A. L. Cook, D. B. Harper, T. A. Berkoff, S. T. Seaman, J. E. Collins, M. A. Fenn, R. R. Rogers |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 15, no. 23 ; Nr. 15, no. 23 (2015-12-07), S.13453-13473 |
| Datensatznummer |
250120205
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| Publikation (Nr.) |
 copernicus.org/acp-15-13453-2015.pdf |
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| Zusammenfassung |
| Linear particle depolarization ratio is presented for three case studies
from the NASA Langley airborne High Spectral Resolution Lidar-2 HSRL-2).
Particle depolarization ratio from lidar is an indicator of non-spherical
particles and is sensitive to the fraction of non-spherical particles and
their size. The HSRL-2 instrument measures depolarization at three
wavelengths: 355, 532, and 1064 nm. The three measurement cases
presented here include two cases of dust-dominated aerosol and one case of
smoke aerosol. These cases have partial analogs in earlier HSRL-1
depolarization measurements at 532 and 1064 nm and in literature, but the
availability of three wavelengths gives additional insight into different
scenarios for non-spherical particles in the atmosphere. A case of
transported Saharan dust has a spectral dependence with a peak of 0.30 at
532 nm with smaller particle depolarization ratios of 0.27 and 0.25 at 1064
and 355 nm, respectively. A case of aerosol containing locally generated
wind-blown North American dust has a maximum of 0.38 at 1064 nm, decreasing
to 0.37 and 0.24 at 532 and 355 nm, respectively. The cause of the
maximum at 1064 nm is inferred to be very large particles that have not
settled out of the dust layer. The smoke layer has the opposite spectral
dependence, with the peak of 0.24 at 355 nm, decreasing to 0.09 and 0.02 at
532 and 1064 nm, respectively. The depolarization in the smoke case may be explained by
the presence of coated soot aggregates. We note that in these specific case
studies, the linear particle depolarization ratio for smoke and
dust-dominated aerosol are more similar at 355 nm than at 532 nm, having
possible implications for using the particle depolarization ratio at a single
wavelength for aerosol typing. |
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