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Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial

Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial
Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial
This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktic foraminiferal fauna following high salinities during marine isotopic stage (MIS) 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea sea surface temperature (SST) increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.
1814-9332
941-955
Trommer, G.
1fbe6fe9-f95c-4217-8932-8f038b9e2aa0
Siccha, M.
dfdcc005-025a-49ce-b0ba-c178d0cad28b
Rohling, E.J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Grant, K.
f9d9fa1b-62f3-4e90-a6f0-b46bc213fdb2
van der Meer, M.T.J.
b200c31e-9fef-4793-9b84-c9c20aa120ce
Schouten, S.
86c33c8e-38d4-432b-b669-e6ae6a7294ea
Baranowski, U.
3de28a14-4ae9-4eac-8e29-e350de76d104
Kucera, M.
1dfd204d-24e1-4e03-b465-c60bb4ac74f7
Trommer, G.
1fbe6fe9-f95c-4217-8932-8f038b9e2aa0
Siccha, M.
dfdcc005-025a-49ce-b0ba-c178d0cad28b
Rohling, E.J.
a2a27ef2-fcce-4c71-907b-e692b5ecc685
Grant, K.
f9d9fa1b-62f3-4e90-a6f0-b46bc213fdb2
van der Meer, M.T.J.
b200c31e-9fef-4793-9b84-c9c20aa120ce
Schouten, S.
86c33c8e-38d4-432b-b669-e6ae6a7294ea
Baranowski, U.
3de28a14-4ae9-4eac-8e29-e350de76d104
Kucera, M.
1dfd204d-24e1-4e03-b465-c60bb4ac74f7

Trommer, G., Siccha, M., Rohling, E.J., Grant, K., van der Meer, M.T.J., Schouten, S., Baranowski, U. and Kucera, M. (2011) Sensitivity of Red Sea circulation to sea level and insolation forcing during the last interglacial. Climate of the Past, 7 (3), 941-955. (doi:10.5194/cp-7-941-2011).

Record type: Article

Abstract

This study investigates the response of Red Sea circulation to sea level and insolation changes during termination II and across the last interglacial, in comparison with termination I and the Holocene. Sediment cores from the central and northern part of the Red Sea were investigated by micropaleontological and geochemical proxies. The recovery of the planktic foraminiferal fauna following high salinities during marine isotopic stage (MIS) 6 took place at similar sea-level stand (~50 m below present day), and with a similar species succession, as during termination I. This indicates a consistent sensitivity of the basin oceanography and the plankton ecology to sea-level forcing. Based on planktic foraminifera, we find that increased water exchange with the Gulf of Aden especially occurred during the sea-level highstand of interglacial MIS 5e. From MIS 6 to the peak of MIS 5e, northern Red Sea sea surface temperature (SST) increased from 21 °C to 25 °C, with about 3 °C of this increase taking place during termination II. Changes in planktic foraminiferal assemblages indicate that the development of the Red Sea oceanography during MIS 5 was strongly determined by insolation and monsoon strength. The SW Monsoon summer circulation mode was enhanced during the termination, causing low productivity in northern central Red Sea core KL9, marked by high abundance of G. sacculifer, which – as in the Holocene – followed summer insolation. Core KL11 records the northern tip of the intruding intermediate water layer from the Gulf of Aden and its planktic foraminifera fauna shows evidence for elevated productivity during the sea-level highstand in the southern central Red Sea. By the time of MIS 5 sea-level regression, elevated organic biomarker BIT values suggest denudation of soil organic matter into the Red Sea and high abundances of G. glutinata, and high reconstructed chlorophyll-a values, indicate an intensified NE Monsoon winter circulation mode. Our results imply that the amplitude of insolation fluctuations, and the resulting monsoon strength, strongly influence the Red Sea oceanography during sea-level highstands by regulating the intensity of water exchange with the Gulf of Aden. These processes are responsible for the observation that MIS 5e/d is characterized by higher primary productivity than the Holocene.

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Published date: 2011
Organisations: Paleooceanography & Palaeoclimate

Identifiers

Local EPrints ID: 201429
URI: http://eprints.soton.ac.uk/id/eprint/201429
ISSN: 1814-9332
PURE UUID: 883ade50-b071-439b-a7fe-27052f448199
ORCID for E.J. Rohling: ORCID iD orcid.org/0000-0001-5349-2158

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Date deposited: 27 Oct 2011 13:16
Last modified: 15 Mar 2024 02:47

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Contributors

Author: G. Trommer
Author: M. Siccha
Author: E.J. Rohling ORCID iD
Author: K. Grant
Author: M.T.J. van der Meer
Author: S. Schouten
Author: U. Baranowski
Author: M. Kucera

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