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| Titel |
A reanalysis of MODIS fine mode fraction over ocean using OMI and daily GOCART simulations |
| VerfasserIn |
T. A. Jones, S. A. Christopher |
| 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 ; 11, no. 12 ; Nr. 11, no. 12 (2011-06-22), S.5805-5817 |
| Datensatznummer |
250009859
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| Publikation (Nr.) |
 copernicus.org/acp-11-5805-2011.pdf |
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| Zusammenfassung |
Using daily Goddard Chemistry Aerosol Radiation and Transport (GOCART) model
simulations and columnar retrievals of 0.55 μm aerosol optical
thickness (AOT) and fine mode fraction (FMF) from the Moderate Resolution
Imaging Spectroradiometer (MODIS), we estimate the satellite-derived aerosol
properties over the global oceans between June 2006 and May 2007 due to
black carbon (BC), organic carbon (OC), dust (DU), sea-salt (SS), and
sulfate (SU) components. Using Aqua-MODIS aerosol properties embedded in the
CERES-SSF product, we find that the mean MODIS FMF values for each aerosol
type are SS: 0.31 ± 0.09, DU: 0.49 ± 0.13, SU: 0.77 ± 0.16, and
(BC + OC): 0.80 ± 0.16. We further combine information from the ultraviolet
spectrum using the Ozone Monitoring Instrument (OMI) onboard the Aura
satellite to improve the classification process, since dust and carbonate
aerosols have positive Aerosol Index (AI) values >0.5 while other aerosol
types have near zero values. By combining MODIS and OMI datasets, we were
able to identify and remove data in the SU, OC, and BC regions that were not
associated with those aerosol types.
The same methods used to estimate aerosol size characteristics from MODIS
data within the CERES-SSF product were applied to Level 2 (L2) MODIS aerosol
data from both Terra and Aqua satellites for the same time period. As
expected, FMF estimates from L2 Aqua data agreed well with the CERES-SSF
dataset from Aqua. However, the FMF estimate for DU from Terra data
was significantly lower (0.37 vs. 0.49) indicating that sensor calibration,
sampling differences, and/or diurnal changes in DU aerosol size
characteristics were occurring. Differences for other aerosol types were
generally smaller. Sensitivity studies show that a difference of 0.1 in the
estimate of the anthropogenic component of FMF produces a corresponding
change of 0.2 in the anthropogenic component of AOT (assuming a unit value
of AOT). This uncertainty would then be passed along to any
satellite-derived estimates of anthropogenic aerosol radiative effects. |
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