Details

Autor(en) / Beteiligte

• Yamagami, Y.
• Tozuka, T.

Titel

Interannual variability of South Equatorial Current bifurcation and western boundary currents along the Madagascar coast

Ist Teil von

• Journal of geophysical research. Oceans, 2015-12, Vol.120 (12), p.8551-8570

Ort / Verlag

Washington: Blackwell Publishing Ltd

Erscheinungsjahr

2015

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• The South Equatorial Current (SEC) in the southern Indian Ocean bifurcates at the east coast of Madagascar into the Northeast and Southeast Madagascar Currents (NEMC and SEMC, respectively). In observational and reanalysis data, interannual variations of the NEMC and SEMC transports are strongly correlated with those of the SEC transport, rather than those of the SEC bifurcation latitude (SBL). Their dynamical mechanisms are then examined based on the Time‐Dependent Island Rule for the first time. It is shown that interannual anomalies of the SBL as well as the NEMC and SEMC transports are predominantly a response to the anomalous inflow from the ocean interior that is determined by the meridional interior transport. This, in turn, is a result of westward propagating Rossby waves induced by wind stress curl anomalies mainly in 60°E–90°E. The above mechanism is contrasted with that of the seasonal variation, where the local transport driven by wind stress around the island plays a role. Furthermore, the interannual variations of the SBL and the NEMC and SEMC transports are significantly correlated with the Niño 3.4 index with 5–15 months lag. It is suggested that diabatic heating anomalies associated with the El Niño/Southern Oscillation (ENSO) along with a local process in the southeastern Indian Ocean may generate wind stress curl anomalies over the southern Indian Ocean. Key Points: Interannual variations of western boundary currents along Madagascar are investigated These interannual anomalies are responses to the anomalous meridional interior transport The anomalous interior transport is generated by wind stress curl anomalies associated with ENSO