Actualité scientifique
H*(/5"(3*$5/-#$
N° 466
October 2014
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Peru: towards better forecasting
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(© INSU / H. Barrois) The measuring instrument OCARINA during the oceanographic campaign AMOP.
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Current system, which runs along the Peruvian and Chilean coasts, boasts exceptional
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should eventually enable a regional modelling platform to be set up integrating the
oceanic, biogeochemical and atmospheric components of the Peru-Chile upwelling.
Good to know
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movement causes the deep, cold, nutrient-rich waters to rise up.
Oxygen minimum zones are zones with a reduced oxygen content located at the eastern margins of the tropical oceans, at a
depth of 50 to 1000 metres. Underlying the oxygenated surface waters, they currently cover almost 10% of the surface area
of the world’s ocean.
CONTACTS
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To better understand how these
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upwelling process and therefore the
biological productivity of the Humboldt
system, the IRD and its Peruvian partners,
the IGP and the IMARPE, have been
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An initial high-resolution study shows that
off Peru the ocean layer called «oxygen
minimum» where life is limited is sensitive
to the intensity of the seasonal current from
the equator that brings water containing little
oxygen to the coastal ecosystem. Thus,
this current called «secondary Tsuchiya
jet» indirectly impacts from the equator the
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Chilean coasts.
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A second modelling study provides
information that gives a better understanding
of the biological response in Peru’s
upwelling to disturbances that occur in the
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it is the action of coastal winds that regulates
surface temperature variations off Peru, on
timescales of around two months. Contrary
to what researchers previously believed,
at these frequencies, the equatorial ocean
waves called Kelvin that spread from west
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ocean, have little effects on the surface.
They do, however, spread along the coast
at around 50 metres deep, modifying the
vertical thermal structure along the way
and thus modulating the mechanical action
of the winds that generate the upwelling
process in the Peruvian open sea.
G,,$"0(#$1+)/,,(52$-+&4A$*+1'(5/)$-("0 in situ
measurements (oceanographic campaigns
recently carried out as part of the AMOP
project) help improve our understanding of
the interactions between biogeochemistry,
atmospheric circulation and oceanic
circulation. They should lead to a dynamic
modelling platform being set up for the
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which are oxygen, wind patterns and Kelvin
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Coordination
Gaëlle Courcoux
Information and Culture
Department
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www.ird.fr/la-mediatheque
Partners
Institut de Géophysique du Pérou (IGP), Institut des
mers du Pérou (IMARPE), GEOMAR Helmholtz
Y/5"&/$<+&$Z*/.5$B/#/.&*0$[(/,$(5$\/&1.5:>$]+&4$
funded by EurOcean, ESA, CNES and IRD.
References
MONTES I., DEWITTE BORIS, GUTKNECHT E., PAULMIER
AURÉLIEN, DADOU I., OSCHLIES A., GARÇON VÉRONIQUE.
High-resolution modeling of the Eastern Tropical
F.*(3*$ +@:2/5$ 1(5(1%1$ ^+5/6$ H/5#("(9(":$ "+$ "0/$
tropical oceanic circulation, J. Geophys. Res. Oceans,
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Media Contact
Cristelle DUOS
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ILLIG SERENA, DEWITTE BORIS, GOUBANOVA K., CAMBON G.,
BOUCHAREL J., MONETTI F., ROMERO C., PURCA S., FLORES
R. (2014), Forcing mechanisms of intraseasonal SST
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Res. OceansA$QQPA$)+(6QM>QMMS_SMQK`YMMPVVP>
Contacts
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Daina Rechner
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UMR Laboratoire d’études en géophysique et
océanographie spatiales - LEGOS (IRD / CNES
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LMI Dynamiques du système du courant de
Humboldt - DISCOH (IRD / IMARPE)
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44 boulevard de Dunkerque,
CS 90009
13572 Marseille Cedex 02
France
© IRD/DIC, Juillet 2014 - Conception et réalisation graphique : L. CORSINI
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The Humboldt Current provides Peru and
Chile with waters containing the largest
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which alone provides 5 to 10% of the world’s
catches, owes its exceptional productivity
to the nutrients provided by upwellings
of deep, cold, nutrient-rich water along
the coasts. But this phenomenon, called
«upwelling» has a very variable intensity
due to the variability of the currents in the
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climate forcing mechanisms are added.