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| Titel |
A theoretical study of the effect of subsurface oceanic bubbles on the enhanced aerosol optical depth band over the southern oceans as detected from MODIS and MISR |
| VerfasserIn |
M. Christensen, J. Zhang, J. S. Reid, X. Zhang, E. J. Hyer, A. Smirnov |
| 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. 5 ; Nr. 8, no. 5 (2015-05-21), S.2149-2160 |
| Datensatznummer |
250116365
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| Publikation (Nr.) |
 copernicus.org/amt-8-2149-2015.pdf |
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| Zusammenfassung |
| Submerged oceanic bubbles, which have a much longer life span than whitecaps
or bubble rafts, have been hypothesized to increase the water-leaving
radiance and thus affect satellite-based estimates of water-leaving radiance
to non-trivial levels. This study explores this effect further to determine
whether such bubbles are of sufficient magnitude to impact satellite aerosol
optical depth (AOD) retrievals through perturbation of the lower boundary
conditions. There has been significant discussion in the community
regarding the high positive biases in retrieved AODs in many remote ocean
regions. In this study, for the first time, the effects of oceanic bubbles
on satellite retrievals of AOD are studied by using a linked Second Simulation
of a Satellite Signal in the Solar Spectrum (6S) atmospheric and HydroLight
oceanic radiative transfer models. The results suggest an insignificant
impact on AOD retrievals in regions with near-surface wind speeds of less
than 12 m s−1. However, the impact of bubbles on aerosol retrievals
could be on the order of 0.02–0.04 for higher wind conditions within the
scope of our simulations (e.g., winds < 20 m −1. This bias is
propagated to global scales using 1 year of Moderate Resolution Imaging
Spectroradiometer (MODIS) and Advanced Microwave Scanning Radiometer EOS
(AMSR-E) data to investigate the possible impacts of oceanic bubbles on an
enhanced AOD belt observed over the high-latitude southern oceans (also
called the enhanced southern oceans anomaly, or ESOA) by some passive satellite
sensors. Ultimately, this study is supportive of the null hypothesis:
submerged bubbles are not the major contributor to the ESOA feature. This
said, as retrievals progress to higher and higher resolutions, such as from
airborne platforms, the uniform bubble correction in clean marine conditions
should probably be separately accounted for against individual bright
whitecaps and bubble rafts. |
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