The late Quaternary history of the South Asian monsoon - Die spätquartäre Entwicklung des Südasiatischen Monsuns

• Main Author: Gebregiorgis, Daniel
• Format: Thesis
• Language: English
• Published: 2016
• Subjects: Indian; Planktonic foraminifera
• Online Access: https://oceanrep.geomar.de/id/eprint/34616/; https://oceanrep.geomar.de/id/eprint/34616/1/Dissertation_Daniel_Gebregiorgis_2016.pdf

The Indian summer or South Asian monsoon (SAM) is a major component of the global climate system that dominates weather patterns and impacts the livelihood of billions of people across the subcontinent. Despite significant improvements over the past decade, the SAM remains difficult to predict and to model. This is directly related to the fact that instrumental records of monsoon precipitation at most date back few centuries. Consequently, the need to generate proxy records of monsoon precipitation and analysis of paleoclimate data is crucial to understand the various forcing mechanism of the monsoon on different timescales. In this thesis, the link between interhemispheric insolation changes and monsoon precipitation is explored and a working hypothesis is provided. High-resolution paleoclimate datasets have been generated from three sediment cores in the Andaman Sea. I develop potential proxies of SAM precipitation and perform paleoclimate time series analysis to better understand orbital and sub-orbital forcing mechanisms of the monsoon. The first continuous long-term high resolution records of monsoon precipitation based on paired Mg/Ca and δ18O analyses of near surface dwelling planktonic foraminifera are presented, from which I estimate sea surface temperature (SST) and seawater δ18O (δ18Osw). In addition, monsoon intensity changes are evaluated using proxies such as Ba/Ca, x-ray fluorescence (XRF) Ti/Ca, and Si/Al, which have been associated with the monsoon via different causal linkages