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| Titel |
Seasonal cycles of surface layer salinity in the Pacific 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 ; 6, no. 3 ; Nr. 6, no. 3 (2010-08-24), S.775-787 |
| Datensatznummer |
250003585
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| Publikation (Nr.) |
 copernicus.org/os-6-775-2010.pdf |
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| Zusammenfassung |
The seasonal variability of surface layer salinity (SLS) is examined in the
Pacific Ocean between 40° S and 60° N using a variety of data sources.
Significant seasonal cycles were found in 5 regions: 1) The western North
Pacific, 2) The northeastern North Pacific and Alaska gyre, 3) the
intertropical convergence zone (ITCZ), 4) an area of the central North
Pacific north of the Hawaiian Islands, 5) the central South Pacific along
10–20° S. Amplitudes range from 0.1 to > 0.5. The largest amplitudes are
in the tropical band and the western North Pacific. Maximum salinity is
obtained in late (northern) winter in the western North Pacific, late winter
and early spring in the northeastern North Pacific, early summer in the ITCZ
area, late summer and early fall in the central North Pacific area and
(austral) winter in the central South Pacific. Large areas of the Pacific
have no significant seasonal variation in SLS.
Seasonal variability of evaporation rate, precipitation rate and the
difference between them (E-P) were calculated from the OAFlux and Global
Precipitation Climatology Project datasets. Typical amplitudes of E-P are
0.1–1 × 10−4 kg m−2 s−1. The seasonal variability of E-P is
largely dominated by variability in evaporation in the western North Pacific
and precipitation elsewhere. The largest amplitudes are in areas along the
edge of the western North Pacific and in the far eastern tropical Pacific
around 10° N. Phases in these areas indicate maximum E-P in mid- to late
winter in these areas of large amplitude. The closest correspondence between
E-P and SLS is in the ITCZ. E-P was combined with seasonal variation of the
mixed-layer depth to calculate the freshwater flux forcing term of the SLS
balance equation. The term was found to be similar in magnitude and
distribution to E-P. Some other terms of the SLS balance were calculated.
Horizontal advection was found to have seasonal cycles in a region near the
equator. Entrainment was found to be mostly not significant except for a
small region along 2.5–7.5° N in the eastern Pacific.
Averaged spatially over large areas in the western North Pacific, ITCZ,
South Pacific and northern North Pacific, the seasonal cycle is mostly a
balance between changes in SLS and E-P, with entrainment and advection
playing relatively minor roles.
This work highlights the potentially significant role of surface salinity in
the hydrologic cycle and in subtropical mode water formation. It can also
help to interpret measurements that will soon be available from the Aquarius
and SMOS (Soil Moisture and Ocean Salinity) satellite missions. |
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