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| Burls, N. J.; Reason, C. J. C.; Penven, Pierrick; Philander, S. G.. |
| Sea surface temperature in the central-eastern equatorial Atlantic has a seasonal cycle far bigger than that of the Pacific, but interannual anomalies smaller than those of the Pacific. Given the amplitude of seasonal SST variability, one wonders whether the seasonal cycle in the Atlantic is so dominant that it is able to strongly influence the evolution of its interannual variability. In this study, interannual upper-ocean variability within the tropical Atlantic is viewed from an energetics perspective, and the role of ocean dynamics, in particular the role of ocean memory, within zonal mode events is investigated. Unlike in the Pacific where seasonal and interannual variability involve distinctly different processes, the results suggest that the latter... |
| Tipo: Text |
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| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00130/24169/22260.pdf |
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| Dilmahamod, Ahmad Fehmi; Aguiar-gonzalez, B.; Penven, P.; Reason, C. J. C.; De Ruijter, W. P. M.; Malan, N.; Hermes, J. C.. |
| South Indian Ocean eddies (SIDDIES), originating from a high evaporation region in the eastern Indian Ocean, are investigated by tracking individual eddies from satellite data and co‐located Argo floats. A subsurface‐eddy identification method, based on its steric dynamic height anomaly, is devised to assign Argo profiles to surface eddies (surfSIDDIES) or subsurface eddies (subSIDDIES). These westward‐propagating, long‐lived features (>3 months) prevail over a preferential latitudinal band, forming a permanent structure linking the eastern to the western Indian Ocean, that we call the 'SIDDIES Corridor'. Key features have been revealed in the mean thermohaline vertical structure of these eddies. Anticyclonic SIDDIES are characterized by positive... |
| Tipo: Text |
Palavras-chave: South Indian Ocean; Eddy corridor; Surface and subsurface eddies; Long-lived eddies; Eddy demography; Heat; Freshwater fluxes. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00440/55194/56670.pdf |
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| Dilmahamod, Ahmad Fehmi; Penven, Pierrick; Aguiar gonzalez, B.; Reason, C. J. C.; Hermes, J. C.. |
| The South‐East Madagascar Bloom occurs in an oligotrophic region of the South‐West Indian Ocean. Phase‐locked to austral summer, this sporadic feature exhibits substantial temporal and spatial variability. Several studies, with different hypotheses, have focused on the initiation mechanism triggering the bloom but none has been as yet clearly substantiated. With 19‐years of ocean colour dataset available as well as in‐situ measurements (Argo profiles), the time is ripe to review this feature. The bloom is characterized in a novel manner and a new bloom index is suggested, yielding 11 bloom years, including 3 major bloom years (1999, 2006 and 2008). Spatially, the bloom varies from a mean structure (22° S‐32° S; 50° E‐∼70°E) both zonally and meridionally. A... |
| Tipo: Text |
Palavras-chave: South-East Madagascar Bloom; South-East Madagascar Current; La Nina; Cyanobacterial bloom. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00482/59338/62118.pdf |
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| Chevane, C. M.; Penven, Pierrick; Nehama, F. P. J.; Reason, C. J. C.. |
| The Sofala Bank, a wide shelf located along the central coast of Mozambique, hosts tides with high amplitudes. The Regional Ocean Modelling System (ROMS) was used to analyse the tidal currents on the bank and to investigate their effects on the stratification and generation of tidal fronts. During spring tides, barotropic tidal currents with maximum values ranging from 40 cm s–1 to 70 cm s–1 are found on the central bank. The major axis of the tidal ellipses for M2 and S2 follow a cross-shelf direction with mainly anticlockwise rotation. Similar to observations, three distinct regimes occur: (i) a warm well-mixed region on the inner shelf where the depths are <30 m; (ii) a wellmixed colder region above the shelf edge; and (iii) a stratified region... |
| Tipo: Text |
Palavras-chave: Barotropic tidal currents; ROMS; Sea surface temperature; Shallow seas; Tidal front. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00362/47276/47852.pdf |
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| Dilmahamod, A. F.; Penven, Pierrick; Aguiar‐gonzález, B.; Reason, C. J. C.; Hermes, J. C.. |
| The South‐East Madagascar Bloom, one of the most compelling biogeochemical features of the Indian Ocean, occurs sporadically during austral summer in the oligotrophic waters south‐east of Madagascar, where it can cover up to 1% of the global ocean surface area. Its spatial extension and its timing are highly variable. A high‐resolution biophysical model is used to investigate a previous hypothesis that the onset of a particular circulation of the South‐East Madagascar Current advects fresher and nutrient‐rich waters eastward, feeding the bloom. The model is able to reproduce an intermittent phytoplankton bloom with large spatial variability but in the subsurface layers, as well as the presence of an irregular retroflection of the South‐East Madagascar... |
| Tipo: Text |
Palavras-chave: South-East Madagascar Bloom; South-West Indian Ocean; Phytoplankton Bloom; Biogeochemical Modeling; South-East Madagascar Current. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00631/74325/73965.pdf |
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