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| Titel |
Surface circulation and upwelling patterns around Sri Lanka |
| VerfasserIn |
A. Vos, C. B. Pattiaratchi, E. M. S. Wijeratne |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 11, no. 20 ; Nr. 11, no. 20 (2014-10-30), S.5909-5930 |
| Datensatznummer |
250117657
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| Publikation (Nr.) |
 copernicus.org/bg-11-5909-2014.pdf |
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| Zusammenfassung |
| Sri Lanka occupies a unique location within the equatorial belt in the
northern Indian Ocean, with the Arabian Sea on its western side and the Bay
of Bengal on its eastern side, and experiences bi-annually reversing monsoon
winds. Aggregations of blue whale (Balaenoptera musculus) have been
observed along the southern coast of Sri Lanka during the northeast (NE)
monsoon, when satellite imagery indicates lower productivity in the surface
waters. This study explored elements of the dynamics of the surface
circulation and coastal upwelling in the waters around Sri Lanka using
satellite imagery and numerical simulations using the Regional Ocean
Modelling System (ROMS). The model was run for 3 years to examine the
seasonal and shorter-term (~10 days) variability. The results
reproduced correctly the reversing current system, between the Equator and
Sri Lanka, in response to the changing wind field: the eastward flowing
Southwest Monsoon Current (SMC) during the southwest (SW) monsoon
transporting 11.5 Sv (mean over 2010–2012) and the westward flowing
Northeast Monsoon Current (NMC) transporting 9.6 Sv during the NE monsoon,
respectively. A recirculation feature located to the east of Sri Lanka during
the SW monsoon, the Sri Lanka Dome, is shown to result from the interaction
between the SMC and the island of Sri Lanka. Along the eastern and western
coasts, during both monsoon periods, flow is southward converging along the
southern coast. During the SW monsoon, the island deflects the eastward
flowing SMC southward, whilst along the eastern coast, the southward flow
results from the Sri Lanka Dome recirculation. The major upwelling region,
during both monsoon periods, is located along the southern coast, resulting
from southward flow converging along the southern coast and subsequent
divergence associated with the offshore transport of water. Higher surface
chlorophyll concentrations were observed during the SW monsoon. The location
of the flow convergence and hence the upwelling centre was dependent on the
relative strengths of wind-driven flow along the eastern and western coasts:
during the SW (NE) monsoon, the flow along the western (eastern) coast was
stronger, migrating the upwelling centre to the east (west). |
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