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| Titel |
Aerosol optical depth and fine-mode fraction retrieval over East Asia using multi-angular total and polarized remote sensing |
| VerfasserIn |
T. Cheng, X. Gu, D. Xie, Z. Li, T. Yu, H. Chen |
| 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 ; 5, no. 3 ; Nr. 5, no. 3 (2012-03-06), S.501-516 |
| Datensatznummer |
250002625
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| Publikation (Nr.) |
 copernicus.org/amt-5-501-2012.pdf |
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| Zusammenfassung |
| A new aerosol retrieval algorithm using multi-angular total and polarized
measurements is presented. The algorithm retrieves aerosol optical depth
(AOD), fine-mode fraction (FMF) for studying the impact of aerosol on
climate change. The retrieval algorithm is based on a lookup table (LUT)
method, which assumes that one fine and one coarse lognormal aerosol modes
can be combined with proper weightings to represent the ambient aerosol
properties. To reduce the ambiguity in retrieval algorithm, the key
characteristics of aerosol model over East Asia are constrained using the
cluster analysis technique based on the AERONET sun-photometer observation
over East Asia, and the fine and coarse modes are not fixed but can vary. A
mixing model of bare soil and green vegetation spectra and the Nadal and
Breon model for the bidirectional polarized reflectance factor (BPDF) were
used to simulate total and polarized surface reflectance of East Asia. By
applying the present algorithm to POLDER measurements, three different
aerosol cases of clear, polluted and dust are analyzed to test the
algorithm. The comparison of retrieved aerosol optical depth (AOD) and
fine-mode fraction (FMF) with those of AERONET sun-photometer observations
show reliable results. Preliminary validation is encouraging. Using the new
aerosol retrieval algorithm for multi-angular total and polarized
measurements, the spatial and temporal variability of anthropogenic aerosol
optical properties over East Asia, which were observed during a heavy
polluted event, were analyzed. Exceptionally high values of aerosol optical
depth contributed by fine mode of up to 0.5 (at 0.865 μm), and high
values of fine-mode fraction of up to 0.9, were observed in this case study. |
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