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| Titel |
Characteristics of the seasonal cycle of surface layer salinity in the global ocean |
| VerfasserIn |
F. M. Bingham, G. R. Foltz, M. J. McPhaden |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 8, no. 5 ; Nr. 8, no. 5 (2012-10-30), S.915-929 |
| Datensatznummer |
250005878
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| Publikation (Nr.) |
 copernicus.org/os-8-915-2012.pdf |
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| Zusammenfassung |
The seasonal variability of surface layer salinity (SLS), evaporation (E),
precipitation (P), E-P, advection and vertical entrainment over the
global ocean is examined using in situ salinity data, the National Centers for
Environmental Prediction's Climate System Forecast Reanalysis and a number of
other ancillary data. Seasonal amplitudes and phases are calculated using
harmonic analysis and presented in all areas of the open ocean between
60° S and 60° N. Areas with large amplitude SLS seasonal
variations include: the intertropical convergence zone (ITCZ) in the Atlantic,
Pacific and Indian Oceans; western marginal seas of the Pacific; and the
Arabian Sea. The median amplitude in areas that have statistically
significant seasonal cycles of SLS is 0.19. Between about 60° S and
60° N, 37% of the ocean surface has a statistically significant
seasonal cycle of SLS and 75% has a seasonal cycle of E-P. Phases of SLS
have a bimodal distribution, with most areas in the Northern Hemisphere
peaking in SLS in March/April and in the Southern Hemisphere in
September/October.
The seasonal cycle is also estimated for surface freshwater forcing using a
mixed-layer depth climatology. With the exception of areas near the
western boundaries of the North Atlantic and North Pacific, seasonal
variability is dominated by precipitation. Surface freshwater forcing also
has a bimodal distribution, with peaks in January and July, 1–2 months
before the peaks of SLS. Seasonal
amplitudes and phases calculated for horizontal advection show it to be
important in the tropical oceans.
Vertical entrainment, estimated from mixed-layer heaving, is largest in mid
and high latitudes, with a seasonal cycle that peaks in late winter.
The amplitudes and phases of SLS and surface fluxes compare well in a
qualitative sense, suggesting that much of the variability in SLS is due to
E-P. However, the amplitudes of SLS are somewhat different than would be
expected and the peak of SLS comes typically about one month earlier than
expected. The differences of the amplitudes of the two quantities is largest
in such areas as the Amazon River plume, the Arabian Sea, the ITCZ and the
eastern equatorial Pacific and Atlantic. |
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