PP43A-1442:
The Indian Monsoon Variability over the Past 280,000 Years.
Thursday, 18 December 2014
Gayatri Kathayat1, Hai Cheng1,2, Ashish Sinha3, Christoph Spötl4, R. Lawrence Edwards2, Weiguo Liu5, Haiwei Zhang1, Yanjun Cai6 and Sebastian F. M. Breitenbach7, (1)Xi'an Jiaotong University, Xian, China, (2)University of Minnesota Twin Cities, Minneapolis, MN, United States, (3)California State University Dominguez Hills, Department of Earth Sciences, Torrance, CA, United States, (4)Universität Innsbruck, Institute für Geologie, Innsbruck, Austria, (5)Institute of Earth Environment Chinese Academy of Sciences, Xi'an, China, (6)IEE Institute of Earth Environment, Chinese Academy of Sciences, Xi'an, China, (7)Eidgenössische Technische Hochschule, CH-8092 Zürich, Department of Earth Sciences, Zürich, Switzerland
Abstract:
The Indian summer monsoon (ISM) is a vast interhemispheric climate system, transporting large amount of moisture and heat across the equator from the southern Indian Ocean to the Asian continent. Considerable debate exists whether northern or southern hemisphere climate processes are the dominant drivers of ISM variability on millennium and orbital times scales. We present a high-resolution speleothem oxygen isotope record of ISM from Bittoo cave (BT) in northern India (30°47N, 77°46E, 3000 masl) for the last 280,000 years. Observations and model simulations show that the δ18O of precipitation in this region is inversely correlated with the ISM intensity. The BT δ18O record is characterized by large amplitude fluctuations on both orbital and millennial timescales with notably abrupt δ18O jumps to extremely light/heavy values commonly occurring at the rising and declining limbs of NHSI, respectively. The orbital-scale variations in ISM intensity track Northern Hemisphere Summer Insolation (NHSI) without notable temporal lags, consistent with the East Asian Monsoon (EAM) variability as documented from Chinese speleothem records. The well-dated MIS 3 and MIS 5 portions in the BT δ18O record show no phase difference with their counterparts in EAM speleothem records, suggesting in-phase variability at precession bands. Prominent millennial-scale events in the BT δ18O record correlate with millennial events in the Greenland ice core and EAM speleothem records rather than Antarctic ice core records, thus demonstrating a strong link between NH high latitude climate and low latitude monsoonal climate. A detailed comparison of the BT record with both Antarctic ice core records and sea surface temperature records does not appear to confirm a dominant role of Southern Hemisphere on the ISM through the postulated increased cross-equatorial pressure gradient.
