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| Titel |
Assessing remote polarimetric measurement sensitivities to aerosol emissions using the geos-chem adjoint model |
| VerfasserIn |
B. S. Meland, X. Xu, D. K. Henze, J. Wang |
| 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 ; 6, no. 12 ; Nr. 6, no. 12 (2013-12-10), S.3441-3457 |
| Datensatznummer |
250085130
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| Publikation (Nr.) |
 copernicus.org/amt-6-3441-2013.pdf |
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| Zusammenfassung |
| Uncertainties in aerosol sources, microphysical properties, and global
distributions undermine efforts to evaluate the radiative impacts of
atmospheric aerosols. In this work, we investigate the feasibility of using
remote polarimetric measurements for constraining aerosol and aerosol
precursor emissions in light of these uncertainties. A model that
incorporates a radiative transfer model with forward and adjoint chemical
transport models has been applied to quantify the sensitivity of the
reflectance at the top of atmosphere over land to aerosol emissions and
microphysical properties. A set of simulated satellite observations, one
intensity based and one capable of polarimetric measurements, are used to
illustrate differences in the assimilation potential between the two. It is
found that the sensitivity of the polarized reflectance to aerosol and
aerosol precursor emissions tends to be significantly higher than that of the
intensity for cases of non-absorbing aerosols. This is true even when the
polarimetric sampling scheme is spatially sparser than that of the intensity
sampling. This framework allows us to quantify upper limits on the
uncertainties in the aerosol microphysical properties for which a 50%
change in aerosol emissions is detectable using these simulated observations.
It was found that although typical current remote sensing instrumentation
provides retrievals of the refractive index and effective radius with
accuracies within acceptable limits to detect a 50% change in emissions,
retrievals of the effective variance contain uncertainties too large to
detect these changes in emissions. These results may guide new applications
of polarimetric measurements to constrain aerosol sources, and thus reduce
uncertainty in our broader understanding of the impacts of aerosols on
climate. |
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