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Island mass effect in the Juan Fernández Archipelago (33°S), Southeastern Pacific

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Autor Andrade I.
Autor Sangra P.
Autor Hormazabal S.
Autor Correa-Ramirez M.
Fecha Ingreso 2014-04-05T00:02:32Z
Fecha Disponible 2014-04-05T00:02:32Z
Fecha en Repositorio 2014-04-04
dc.identifier 10.1016/j.dsr.2013.10.009
dc.description.abstract Spatial and temporal variability of the island mass effect (IME; defined as local increases of phytoplankton associated with the presence of islands) at the Juan Fernández Archipelago (JFA) is analyzed using chlorophyll-a (Chl-a) satellite data, altimetry, sea surface temperature, wind, geostrophic currents and net heat flux over a ten year period (2002-2012). The the JFA islands (Robinson Crusoe-Santa Clara (RC-SC) and Alejandro Selkirk (AS)) present wakes with significant Chl-a increases, mainly during spring time. These wakes can reach Chl-a values of one order of magnitude higher (~1mgm-3) than the surrounding oligotrophic waters (<0.1mgm-3). The wakes are similar to von Kármán vortex streets which have been used to explain the impact of IME on Chl-a increases in numerical models. The wakes are formed from a high productivity area in the lee of the island, extending to the oceanic region as high Chl-a patches associated with submesoscale eddies that are detached from the islands and connected by less-productive zones. This pattern coincides with previous models that predict the effects of island-generated flow perturbations on biological production variability. The IME is a recurrent feature of islands that has even been observed in decadal average fields. In such average fields, the Chl-a values in RC-SC and AS islands can exceed values found in a Control Zone (a zone without islands) by ~50% and 30%, respectively. Seasonal and interannual variability reveals that, as a consequence of the IME, the winter Chl-a maximum associated with the development of winter convection and mesoscale eddies that propagate from the continental zone, promote that the Chl-a maximum extends towards spring. The IME has an impact on the island on both a local as well as a more regional scale that affects an area of ~40,000km2 (1°Latitude×4°Longitude) centered on the islands. The transport of high productivity patches associated with submesoscale eddies may be responsible for IME propagation at a regional scale. Around the islands, the presence of a weak oceanic incident flow and strong and recurrent wind-wakes, suggest that the generation of Chl-a wakes result from a combined effect between both forcings. © 2013 Elsevier Ltd. en_US
dc.source Deep-Sea Research Part I: Oceanographic Research Papers
Link Descarga dc.source.uri
Title dc.title Island mass effect in the Juan Fernández Archipelago (33°S), Southeastern Pacific en_US
Tipo dc.type Article
dc.description.keywords Chlorophyll a; Island wakes; Mass effects; Sub-mesoscale eddies; Vortex street; Chlorophyll; Ocean currents; Productivity; Vortex flow; Wakes; archipelago; biological production; chlorophyll a; geostrophic flow; heat flux; mesoscale eddy; oligotrophic environment; phytoplankton; satellite altimetry; satellite data; sea surface temperature; seasonality; spatiotemporal analysis; vortex; wake; Juan Fernandez Islands en_US

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