HISTORY AND DYNAMICS OF CLIMATE VARIABILITY IN THE ASIAN MONSOON REGION AND TROPICAL PACIFIC DURING THE LATE HOLOCENE

Persistent Link:
http://hdl.handle.net/10150/145432
Title:
HISTORY AND DYNAMICS OF CLIMATE VARIABILITY IN THE ASIAN MONSOON REGION AND TROPICAL PACIFIC DURING THE LATE HOLOCENE
Author:
Conroy, Jessica
Issue Date:
2011
Publisher:
The University of Arizona.
Rights:
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.
Abstract:
Large-scale climate modes such as the El Niño/Southern Oscillation (ENSO), the Asian monsoon, and the Arctic Oscillation are responsible for much of the Earth’s climate variability. Despite the importance of these modes, we have limited understanding of how they vary on long (multidecadal to millennial) timescales due to the short length of instrumental climate records. Fortunately, climate information stored in natural archives can provide us with information on how these modes varied in the more distant past. Lake sediments are an ideal climate archive since they are continuous, have high temporal resolution, and contain many potential climate proxies. In the present study, I use lake sediment records to assess past climate and environmental changes associated with the El Niño/Southern Oscillation, the Asian monsoon, and the Arctic Oscillation. Exploring modern precipitation variability across the Asian monsoon region, I found that precipitation within this broad area is not coherent, which holds implications for paleorecords that are hypothesized to represent monsoon variability, including many lake sediment records on the Tibetan Plateau. Monsoon precipitation in the Arabian Sea is distinct from precipitation in India and China, and increased precipitation in the Arabian Sea coincides with decreased precipitation in the western North Pacific. Furthermore, only precipitation in southwestern Tibet responds to the Southwest monsoon, whereas precipitation in southeastern Tibet responds to the western North Pacific monsoon. In southwestern Tibet, I have reconstructed dust variability over the last millennium using the lake sediment record from Kiang Co. The sediment record shows a trend toward increasing dust over the 20th century, and our hypothesized dust proxy is positively correlated with the June-November Arctic Oscillation Index. A trend toward more positive Arctic Oscillation Index values as well as higher temperatures over the 20th century likely drove increased dustiness in southwestern Tibet, due the influence of temperature on glaciofluvial sediment availability in the Himalayas. Sediment trap, sediment core data, and modern measurements of local climate and lake water variables at Genovesa Crater Lake, Galápagos, indicate the lake and its sediments respond to local climate variability, with carbonate-rich sediments forming during prolonged dry periods (La Niña events), and organic-rich sediment forming during the warm season and El Niño events. The ratios of silica to calcium and strontium to calcium also reflect cool season SST. Thus, this lake sediment record has potential to provide a record of both seasonal and ENSO variability spanning the Holocene.
Type:
Electronic Dissertation; text
Keywords:
Asian monsoon; dust; Galapagos; lakes; tropical Pacific
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Geosciences
Degree Grantor:
University of Arizona
Advisor:
Overpeck, Jonathan T.

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleHISTORY AND DYNAMICS OF CLIMATE VARIABILITY IN THE ASIAN MONSOON REGION AND TROPICAL PACIFIC DURING THE LATE HOLOCENEen_US
dc.creatorConroy, Jessicaen_US
dc.contributor.authorConroy, Jessicaen_US
dc.date.issued2011-
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.en_US
dc.description.abstractLarge-scale climate modes such as the El Niño/Southern Oscillation (ENSO), the Asian monsoon, and the Arctic Oscillation are responsible for much of the Earth’s climate variability. Despite the importance of these modes, we have limited understanding of how they vary on long (multidecadal to millennial) timescales due to the short length of instrumental climate records. Fortunately, climate information stored in natural archives can provide us with information on how these modes varied in the more distant past. Lake sediments are an ideal climate archive since they are continuous, have high temporal resolution, and contain many potential climate proxies. In the present study, I use lake sediment records to assess past climate and environmental changes associated with the El Niño/Southern Oscillation, the Asian monsoon, and the Arctic Oscillation. Exploring modern precipitation variability across the Asian monsoon region, I found that precipitation within this broad area is not coherent, which holds implications for paleorecords that are hypothesized to represent monsoon variability, including many lake sediment records on the Tibetan Plateau. Monsoon precipitation in the Arabian Sea is distinct from precipitation in India and China, and increased precipitation in the Arabian Sea coincides with decreased precipitation in the western North Pacific. Furthermore, only precipitation in southwestern Tibet responds to the Southwest monsoon, whereas precipitation in southeastern Tibet responds to the western North Pacific monsoon. In southwestern Tibet, I have reconstructed dust variability over the last millennium using the lake sediment record from Kiang Co. The sediment record shows a trend toward increasing dust over the 20th century, and our hypothesized dust proxy is positively correlated with the June-November Arctic Oscillation Index. A trend toward more positive Arctic Oscillation Index values as well as higher temperatures over the 20th century likely drove increased dustiness in southwestern Tibet, due the influence of temperature on glaciofluvial sediment availability in the Himalayas. Sediment trap, sediment core data, and modern measurements of local climate and lake water variables at Genovesa Crater Lake, Galápagos, indicate the lake and its sediments respond to local climate variability, with carbonate-rich sediments forming during prolonged dry periods (La Niña events), and organic-rich sediment forming during the warm season and El Niño events. The ratios of silica to calcium and strontium to calcium also reflect cool season SST. Thus, this lake sediment record has potential to provide a record of both seasonal and ENSO variability spanning the Holocene.en_US
dc.typeElectronic Dissertationen_US
dc.typetexten_US
dc.subjectAsian monsoonen_US
dc.subjectdusten_US
dc.subjectGalapagosen_US
dc.subjectlakesen_US
dc.subjecttropical Pacificen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineGeosciencesen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorOverpeck, Jonathan T.en_US
dc.contributor.committeememberCole, Juliaen_US
dc.contributor.committeememberCohen, Andrewen_US
dc.contributor.committeememberRussell, Joellenen_US
dc.contributor.committeememberQuade, Jayen_US
dc.identifier.proquest11655-
dc.identifier.oclc752261498-
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