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| Titel |
Retrieval of aerosol backscatter, extinction, and lidar ratio from Raman lidar with optimal estimation |
| VerfasserIn |
A. C. Povey, R. G. Grainger, D. M. Peters, J. L. Agnew |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1867-1381
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Measurement Techniques ; 7, no. 3 ; Nr. 7, no. 3 (2014-03-13), S.757-776 |
| Datensatznummer |
250115646
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| Publikation (Nr.) |
 copernicus.org/amt-7-757-2014.pdf |
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| Zusammenfassung |
Optimal estimation retrieval is a form of nonlinear regression
which determines the most probable circumstances that produced
a given observation, weighted against any prior knowledge of the
system. This paper applies the technique to the estimation of
aerosol backscatter and extinction (or lidar ratio) from two-channel
Raman lidar observations. It produces results from simulated and
real data consistent with existing Raman lidar analyses and
additionally returns a more rigorous estimate of its uncertainties
while automatically selecting an appropriate resolution without the
imposition of artificial constraints. Backscatter is retrieved at
the instrument's native resolution with an uncertainty between 2 and
20%. Extinction is less well constrained, retrieved at
a resolution of 0.1–1 km depending on the quality of the
data. The uncertainty in extinction is > 15%, in part due
to the consideration of short 1 min integrations, but is
comparable to fair estimates of the error when using the standard
Raman lidar technique.
The retrieval is then applied to several hours of observation on 19 April 2010
of ash from the Eyjafjallajökull eruption. A depolarising ash layer is found with a lidar ratio of
20–30 sr, much lower values than observed by previous
studies. This potentially indicates a growth of the particles after
12–24 h within the planetary boundary layer. A lower concentration
of ash within a residual layer exhibited a backscatter of
10 Mm−1 sr−1 and lidar ratio of 40 sr. |
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