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A 500,000 year record of Indian summer monsoon dynamics recorded by eastern equatorial Indian Ocean upper water-column structure

A 500,000 year record of Indian summer monsoon dynamics recorded by eastern equatorial Indian Ocean upper water-column structure
A 500,000 year record of Indian summer monsoon dynamics recorded by eastern equatorial Indian Ocean upper water-column structure
The Indian Summer Monsoon (ISM) is an inter-hemispheric and highly variable ocean–atmosphere–land interaction that directly affects the densely populated Indian subcontinent. Here, we present new records of palaeoceanographic variability that span the last 500,000 years from the eastern equatorial Indian Ocean, a relatively under-sampled area of ISM influence. We have generated carbon and oxygen stable isotope records from three foraminiferal species from Ocean Drilling Program Site 758 (5°N, 90°E) to investigate the oceanographic history of this region. We interpret our resultant ??18O (surface-thermocline) record of upper water-column stratification in the context of past ISM variability, and compare orbital phase relationships in our Site 758 data to other climate and monsoon proxies in the region. Results suggest that upper water-column stratification at Site 758, which is dominated by variance at precession and half-precession frequencies (23, 19 and 11 ka), is forced by both local (5°N) insolation and ISM winds. In the precession (23 ka) band, stratification minima at Site 758 lag northern hemisphere summer insolation maxima (precession minima) by 9 ka, which is consistent with Arabian Sea ISM phase estimates and suggests a common wind forcing in both regions. This phase implicates a strong sensitivity to both ice volume and southern hemisphere insolation forcing via latent heat export from the southern subtropical Indian Ocean. Additionally, we find evidence of possible overprinting of millennial-scale events during glacial terminations in our stratification record, which suggests an influence of remote abrupt climate events on ISM dynamics.
Monsoon, Indian Ocean, Stratification, Wind, Precession, Half-precession, Millennial
0277-3791
167-180
Bolton, Clara T.
d3f550f0-1fe9-4d18-8a9c-a61034ab0280
Chang, Liao
83123f49-dd71-43a9-a0b1-d80777231b44
Clemens, Steven C.
4771b217-413b-44b5-887a-2c4762c35a45
Kodama, Kazuto
96c5b79f-73aa-45fd-848e-7e9c4a99be58
Ikehara, Minoru
4bf7fda2-5bee-4c32-a6ed-09765926486e
Medina-Elizalde, Martin
a9ab5d65-88ea-4993-a961-e8fc02166321
Paterson, Greig A.
af24fc9c-0679-4abc-8aed-b8b00326f82a
Roberts, Andrew P.
4f062491-5408-4edb-8dd1-140c6a42e93f
Rohling, Eelco J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Yamamoto, Yuhji
42d60ca7-0033-4346-931c-60531ffc8b30
Zhao, Xiang
99ee573a-4607-40b5-a473-2046d623a2e0
Bolton, Clara T.
d3f550f0-1fe9-4d18-8a9c-a61034ab0280
Chang, Liao
83123f49-dd71-43a9-a0b1-d80777231b44
Clemens, Steven C.
4771b217-413b-44b5-887a-2c4762c35a45
Kodama, Kazuto
96c5b79f-73aa-45fd-848e-7e9c4a99be58
Ikehara, Minoru
4bf7fda2-5bee-4c32-a6ed-09765926486e
Medina-Elizalde, Martin
a9ab5d65-88ea-4993-a961-e8fc02166321
Paterson, Greig A.
af24fc9c-0679-4abc-8aed-b8b00326f82a
Roberts, Andrew P.
4f062491-5408-4edb-8dd1-140c6a42e93f
Rohling, Eelco J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Yamamoto, Yuhji
42d60ca7-0033-4346-931c-60531ffc8b30
Zhao, Xiang
99ee573a-4607-40b5-a473-2046d623a2e0

Bolton, Clara T., Chang, Liao, Clemens, Steven C., Kodama, Kazuto, Ikehara, Minoru, Medina-Elizalde, Martin, Paterson, Greig A., Roberts, Andrew P., Rohling, Eelco J., Yamamoto, Yuhji and Zhao, Xiang (2013) A 500,000 year record of Indian summer monsoon dynamics recorded by eastern equatorial Indian Ocean upper water-column structure. Quaternary Science Reviews, 77, 167-180. (doi:10.1016/j.quascirev.2013.07.031).

Record type: Article

Abstract

The Indian Summer Monsoon (ISM) is an inter-hemispheric and highly variable ocean–atmosphere–land interaction that directly affects the densely populated Indian subcontinent. Here, we present new records of palaeoceanographic variability that span the last 500,000 years from the eastern equatorial Indian Ocean, a relatively under-sampled area of ISM influence. We have generated carbon and oxygen stable isotope records from three foraminiferal species from Ocean Drilling Program Site 758 (5°N, 90°E) to investigate the oceanographic history of this region. We interpret our resultant ??18O (surface-thermocline) record of upper water-column stratification in the context of past ISM variability, and compare orbital phase relationships in our Site 758 data to other climate and monsoon proxies in the region. Results suggest that upper water-column stratification at Site 758, which is dominated by variance at precession and half-precession frequencies (23, 19 and 11 ka), is forced by both local (5°N) insolation and ISM winds. In the precession (23 ka) band, stratification minima at Site 758 lag northern hemisphere summer insolation maxima (precession minima) by 9 ka, which is consistent with Arabian Sea ISM phase estimates and suggests a common wind forcing in both regions. This phase implicates a strong sensitivity to both ice volume and southern hemisphere insolation forcing via latent heat export from the southern subtropical Indian Ocean. Additionally, we find evidence of possible overprinting of millennial-scale events during glacial terminations in our stratification record, which suggests an influence of remote abrupt climate events on ISM dynamics.

Full text not available from this repository.

More information

Published date: October 2013
Keywords: Monsoon, Indian Ocean, Stratification, Wind, Precession, Half-precession, Millennial
Organisations: Geology & Geophysics, Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 359541
URI: https://eprints.soton.ac.uk/id/eprint/359541
ISSN: 0277-3791
PURE UUID: e04f443d-752b-4213-9a7b-3edbe5aaf525
ORCID for Eelco J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

Catalogue record

Date deposited: 04 Nov 2013 10:40
Last modified: 06 Jun 2018 13:06

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