FN Archimer Export Format
PT J
TI Where and how the East Madagascar Current retroflection originates?
BT 
AF Ramanantsoa, Juliano D.
   Penven, Pierrick
   Raj, R. P.
   Renault, L.
   Ponsoni, L.
   Ostrowski, M.
   Dilmahamod, A. F.
   Rouault, M.
AS 1:1,2,3,4;2:5;3:6;4:7,8;5:9;6:10;7:11,12;8:1,3;
FF 1:;2:;3:;4:;5:;6:;7:;8:;
C1 Department of Oceanography University of Cape Town (UCT) ,South Africa
   Norwegian Research Center (NORCE) Bergen, Norway
   Nansen Tutu for Marine Environmental Research Ma‐Re Institute University of Cape Town (UCT) ,South Africa
   Institut Halieutique et des Sciences Marines (IH.SM) Toliara, Madagascar
   Univ. Brest CNRS IRD Ifremer Laboratoire d’Océanographie Physique et Spatiale (LOPS) IUEM Brest ,France
   Nansen Environmental and Remote Sensing Center (NERSC) Bjerknes Center for Climate Research (BCCR) Bergen ,Norway
   Department of Atmospheric and Oceanic Sciences University of California Los Angeles, Los Angeles, USA
   Laboratoire d'Étude en Geophysique et Océanographie Spatiale, IRD, Toulouse, France
   Georges Lemaître Centre for Earth and Climate Research (TECLIM) Earth and Life Institute Université catholique de Louvain Louvain‐la‐Neuve, Belgium
   Institute of Marine Research (IMR) Bergen, Norway
   GEOMAR Helmholtz Centre for Ocean Research Kiel Kiel ,Germany
   Department of Oceanography Dalhousie University HalifaxNova Scotia B3H 4R2, Canada
C2 UNIV CAPE TOWN, SOUTH AFRICA
   NORCE, NORWAY
   UNIV CAPE TOWN, SOUTH AFRICA
   IHSM, MADAGASCAR
   IRD, FRANCE
   NERSC, NORWAY
   UNIV CALIF LOS ANGELES, USA
   IRD, FRANCE
   UNIV CATHOLIC LOUVAIN, BELGIUM
   IMR (BERGEN), NORWAY
   IFM GEOMAR, GERMANY
   UNIV DALHOUSIE, CANADA
UM LOPS
IN WOS Cotutelle UMR
   copubli-france
   copubli-europe
   copubli-int-hors-europe
   copubli-sud
IF 3.938
TC 2
UR https://archimer.ifremer.fr/doc/00732/84401/89431.pdf
LA English
DT Article
DE ;EMC;retroflection;eddies;SICC;bloom phytoplankton;Indian Ocean
AB The East Madagascar Current (EMC) is one of the western boundary currents of the South Indian Ocean. As such, it plays an important role in the climate system by transporting water and heat towards the pole and recirculating to the large-scale Indian Ocean through retroflection modes of its southern extension. Five cruise datasets and remote sensing data from different sensors are used to identify three states of the southern extension of the East Madagascar Current (EMC): early retroflection, canonical retroflection and no retroflection. Retroflections occur 47% of the time. EMC strength regulates the retroflection state, although impinged mesoscale eddies also contribute to retroflection formation. Early retroflection is linked with EMC volume transport. Anticyclonic eddies drifting from the central Indian Ocean to the coast favour early retroflection formation, anticyclonic eddies near the southern tip of Madagascar promote the generation of canonical retroflection, and no retroflection appears to be associated with a lower eddy kinetic energy (EKE). Knowledge of the EMC retroflection state could help predict (1) coastal upwelling south of Madagascar, (2) the southeastern Madagascar phytoplankton bloom, and (3) the formation of the South Indian Ocean Counter Current (SICC). Plain Language Summary Using in situ and satellite observations, we show that the East Madagascar Current (EMC), a strong current flowing along the East Coast of Madagascar, often detaches from the coast before the southern tip of the island and goes directly into the Indian Ocean, the so-called EMC retroflection. The EMC retroflection is characterized by three well-defined forms: early retroflection, canonical retroflection, and no retroflection. The EMC Early Retroflection is an unusual abrupt return current straight to the Indian Ocean without reaching the detachment point, while the EMC Canonical Retroflection returns the mass flow in the vicinity of the southern tip of the island. No retroflection is characterized by the straight propagation of the flow towards the Agulhas Current. These three forms of retroflection are due to the strength of the EMC and the contribution of mesoscale eddies arriving from the Indian Ocean. Retroflections have implications for coastal upwelling strength, Southeast Madagascar phytoplankton bloom occurrences, and South Indian Ocean Counter Current (SICC) formation. 
PY 2021
PD NOV
SO Journal Of Geophysical Research-oceans
SN 2169-9275
PU American Geophysical Union (AGU)
VL 126
IS 11
UT 000723095600033
DI 10.1029/2020JC016203
ID 84401
ER

EF