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Titel |
High-resolution and Monte Carlo additions to the SASKTRAN radiative transfer model |
VerfasserIn |
D. J. Zawada, S. R. Dueck, L. A. Rieger, A. E. Bourassa, N. D. Lloyd, D. A. Degenstein |
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 ; 8, no. 6 ; Nr. 8, no. 6 (2015-06-26), S.2609-2623 |
Datensatznummer |
250116443
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Publikation (Nr.) |
copernicus.org/amt-8-2609-2015.pdf |
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Zusammenfassung |
The Optical Spectrograph and InfraRed Imaging
System (OSIRIS) instrument on board the Odin spacecraft has been
measuring limb-scattered radiance since 2001. The vertical radiance
profiles measured as the instrument nods are inverted, with the aid
of the SASKTRAN radiative transfer model, to obtain vertical
profiles of trace atmospheric constituents. Here we describe two
newly developed modes of the SASKTRAN radiative transfer model:
a high-spatial-resolution mode and a Monte Carlo mode. The
high-spatial-resolution mode is a successive-orders model capable of
modelling the multiply scattered radiance when the atmosphere is not
spherically symmetric; the Monte Carlo mode is intended for use as
a highly accurate reference model. It is shown that the two models
agree in a wide variety of solar conditions to within 0.2 %.
As an example case for both models, Odin–OSIRIS scans were simulated
with the Monte Carlo model and retrieved using the high-resolution
model. A systematic bias of up to 4 % in retrieved ozone number
density between scans where the instrument is scanning up or
scanning down was identified.
The bias is largest when the sun is near the horizon and the solar
scattering angle is far from 90°.
It was found that calculating the
multiply scattered diffuse field at five discrete solar zenith
angles is sufficient to eliminate the bias for typical Odin–OSIRIS
geometries. |
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