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| Titel |
Improvement of aerosol optical depth retrieval from MODIS spectral reflectance over the global ocean using new aerosol models archived from AERONET inversion data and tri-axial ellipsoidal dust database |
| VerfasserIn |
J. Lee, J. Kim, P. Yang, N. C. Hsu |
| 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 ; 12, no. 15 ; Nr. 12, no. 15 (2012-08-06), S.7087-7102 |
| Datensatznummer |
250011372
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| Publikation (Nr.) |
 copernicus.org/acp-12-7087-2012.pdf |
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| Zusammenfassung |
| New over-ocean aerosol models are developed by integrating the inversion
data from the Aerosol Robotic Network (AERONET) sun/sky radiometers with a
database for the optical properties of tri-axial ellipsoid particles. The new aerosol
models allow more accurate retrieval of aerosol optical depth (AOD) from the
Moderate Resolution Imaging Spectroradiometer (MODIS) in the case of high
AOD (AOD > 0.3). The aerosol models are categorized by using the
fine-mode fraction (FMF) at 550 nm and the single-scattering albedo (SSA) at
440 nm from the AERONET inversion data to include a variety of aerosol types
found around the globe. For each aerosol model, the changes in the aerosol
optical properties (AOPs) as functions of AOD are considered to better
represent aerosol characteristics. Comparisons of AODs between AERONET and
MODIS for the period from 2003 to 2010 show that the use of the new aerosol
models enhances the AOD accuracy with a Pearson coefficient of 0.93 and a
regression slope of 0.99 compared to 0.92 and 0.85 calculated using the
MODIS Collection 5 data. Moreover, the percentage of data within an expected
error of ± (0.03 + 0.05 × AOD) is increased from 62% to
64% for overall data and from 39% to 5% for AOD > 0.3.
Errors in the retrieved AOD are further characterized with respect to the
Ångström exponent (AE), scattering angle (Θ), SSA, and air
mass factor (AMF). Due to more realistic AOPs assumptions, the new algorithm
generally reduces systematic errors in the retrieved AODs compared with the
current operational algorithm. In particular, the underestimation of
fine-dominated AOD and the scattering angle dependence of dust-dominated AOD
are significantly mitigated as results of the new algorithm's improved
treatment of aerosol size distribution and dust particle nonsphericity. |
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