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- Title
Migrating subtropical front and Agulhas Return Current affect the southwestern Indian Ocean during the late Quaternary.
- Authors
Naik, D. K.; Saraswat, R.; Khare, N.; Pandey, A. C.; Nigam, R.
- Abstract
The position of sub-tropical front (STF), Agulhas Current (AC) and Agulhas Return Current (ARC) controls the hydrography of southwestern Indian Ocean. Although, equator-ward migration of STF and reduction in Agulhas leakage has been reported during the last glacial period, the fate of ARC during the last glacial-interglacial cycle is not clear. Therefore, in order to understand changes in the position and strength of ARC during the last glacial-interglacial cycle, here we reconstruct hydrographic changes in the southwestern Indian Ocean from temporal variation in planktic foraminiferal abundance, stable isotopic ratio (δ18O) and trace metal ratio (Mg/Ca) of planktic foraminifera Globigerina bulloides in a core collected from the Agulhas Retroflection Region (ARR) in the southwestern Indian Ocean. Increased abundance of G. bulloides suggests that the productivity in the southwestern Indian Ocean increased during glacial period which confirms previous reports of high glacial productivity in the Southern Ocean. The increased productivity was likely driven by a combination of equator-ward migration of subtropical front and westerlies. Increase in relative abundance of Neogloboquadrina pachyderma Dextral suggests warming of ARR leading to strong thermocline in the southwestern Indian Ocean during the last glacial period. We suggest that the warming of Agulhas Retroflection Region was driven by strengthened ARC which shifted to the east of its present location, thus bringing warmer and saltier water to the southwestern Indian Ocean. Therefore, it is inferred that over the last glacial-interglacial cycle, the hydrography of southwestern Indian Ocean was driven by an eastward shift of retroflection region as well as migrating subtropical front.
- Subjects
INDIAN Ocean; HOLOCENE Epoch; MIGRATION time (Chromatography); HYDROGRAPHY; GLACIATION; TRACE metals; CHROMATOGRAPHIC analysis; AGULHAS Current
- Publication
Climate of the Past Discussions, 2013, Vol 9, Issue 5, p5521
- ISSN
1814-9324
- Publication type
Article
- DOI
10.5194/cpd-9-5521-2013