Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos
I present a high- resolution record of Southeast Asian Monsoon (SEAM) evolution compiled from δ18O measurements conducted on five U-Th dated speleothems from Tham Mai Cave in northern Laos (20.75N, 102.65E), a key site at the interface between the Indian and East Asian monsoon systems. The speleothe...
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ftcdlib:qt1cp3q8j9 2023-05-15T16:30:37+02:00 Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos Yang, Hongying 185 2016-01-01 application/pdf http://www.escholarship.org/uc/item/1cp3q8j9 http://n2t.net/ark:/13030/m53n6qnb en eng eScholarship, University of California http://www.escholarship.org/uc/item/1cp3q8j9 qt1cp3q8j9 http://n2t.net/ark:/13030/m53n6qnb public Yang, Hongying. (2016). Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos. UC Irvine: Earth System Science. Retrieved from: http://www.escholarship.org/uc/item/1cp3q8j9 Paleoclimate science Geochemistry Atmospheric sciences Asian Monsoon Holocene Karst Hydrology Oxygen Isotopes Paleoclimate Speleothems dissertation 2016 ftcdlib 2016-10-07T22:55:51Z I present a high- resolution record of Southeast Asian Monsoon (SEAM) evolution compiled from δ18O measurements conducted on five U-Th dated speleothems from Tham Mai Cave in northern Laos (20.75N, 102.65E), a key site at the interface between the Indian and East Asian monsoon systems. The speleothem oxygen isotope records are tied to robust uranium-series dates and indicate the records span from 0.79 to 13 kyr BP with sub-decadal resolution. During the Holocene, the Tham Mai speleothem δ18O records are characterized by lower values during the early to mid-Holocene with increasing values towards the late Holocene. This is similar to trends seen throughout the Asian monsoon region, reflecting the strong insolation control on monsoon strength and ITCZ position. The Younger Dryas is characterized by an abrupt δ18O increase and is synchronous with the even observed in Chinese speleothem records and Greenland ice cores within age uncertainties. This suggests that the SEAM weakened in sync with high-latitude abrupt cooling events. Four speleothems from Tham Mai cave grew contemporaneously from 4,300 years BP to 9,000 years BP. These four samples show a similar δ18O pattern, despite a 1.2‰ between sample δ18O variability is observed. A lumped parameter forward model method (KarstFor model) is used to assess to which extent this 1.2‰ discrepancy can be attributed to hydrological variability. Results suggested that this 1.2‰ discrepancy can be generated due to hydrological variability within one cave. To better interpret interannual δ18O variability in high-resolution oxygen isotope records in the Asian Monsoon region, I utilize existing simulations from a spectrally nudged isotope-enabled general circulation model (IsoGSM) to investigate the climatic controls on δ18Op at four cave locations along the Asian monsoon region. Results show that δ18Op at the four cave sites reflects large-scale ocean-atmosphere processes, instead of local precipitation amount. Spatial correlation with vertical wind shear indicates that δ18Op at all sites is significantly related to monsoon strength and Walker circulation. The spatial correlations with SST and precipitation, suggest that the ENSO likely does play a role and that central Pacific type El Niño events influence precipitation δ18O in Oman and northern Laos, in particular. Doctoral or Postdoctoral Thesis Greenland Greenland ice cores University of California: eScholarship Greenland Indian Pacific |
institution |
Open Polar |
collection |
University of California: eScholarship |
op_collection_id |
ftcdlib |
language |
English |
topic |
Paleoclimate science Geochemistry Atmospheric sciences Asian Monsoon Holocene Karst Hydrology Oxygen Isotopes Paleoclimate Speleothems |
spellingShingle |
Paleoclimate science Geochemistry Atmospheric sciences Asian Monsoon Holocene Karst Hydrology Oxygen Isotopes Paleoclimate Speleothems Yang, Hongying Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos |
topic_facet |
Paleoclimate science Geochemistry Atmospheric sciences Asian Monsoon Holocene Karst Hydrology Oxygen Isotopes Paleoclimate Speleothems |
description |
I present a high- resolution record of Southeast Asian Monsoon (SEAM) evolution compiled from δ18O measurements conducted on five U-Th dated speleothems from Tham Mai Cave in northern Laos (20.75N, 102.65E), a key site at the interface between the Indian and East Asian monsoon systems. The speleothem oxygen isotope records are tied to robust uranium-series dates and indicate the records span from 0.79 to 13 kyr BP with sub-decadal resolution. During the Holocene, the Tham Mai speleothem δ18O records are characterized by lower values during the early to mid-Holocene with increasing values towards the late Holocene. This is similar to trends seen throughout the Asian monsoon region, reflecting the strong insolation control on monsoon strength and ITCZ position. The Younger Dryas is characterized by an abrupt δ18O increase and is synchronous with the even observed in Chinese speleothem records and Greenland ice cores within age uncertainties. This suggests that the SEAM weakened in sync with high-latitude abrupt cooling events. Four speleothems from Tham Mai cave grew contemporaneously from 4,300 years BP to 9,000 years BP. These four samples show a similar δ18O pattern, despite a 1.2‰ between sample δ18O variability is observed. A lumped parameter forward model method (KarstFor model) is used to assess to which extent this 1.2‰ discrepancy can be attributed to hydrological variability. Results suggested that this 1.2‰ discrepancy can be generated due to hydrological variability within one cave. To better interpret interannual δ18O variability in high-resolution oxygen isotope records in the Asian Monsoon region, I utilize existing simulations from a spectrally nudged isotope-enabled general circulation model (IsoGSM) to investigate the climatic controls on δ18Op at four cave locations along the Asian monsoon region. Results show that δ18Op at the four cave sites reflects large-scale ocean-atmosphere processes, instead of local precipitation amount. Spatial correlation with vertical wind shear indicates that δ18Op at all sites is significantly related to monsoon strength and Walker circulation. The spatial correlations with SST and precipitation, suggest that the ENSO likely does play a role and that central Pacific type El Niño events influence precipitation δ18O in Oman and northern Laos, in particular. |
format |
Doctoral or Postdoctoral Thesis |
author |
Yang, Hongying |
author_facet |
Yang, Hongying |
author_sort |
Yang, Hongying |
title |
Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos |
title_short |
Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos |
title_full |
Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos |
title_fullStr |
Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos |
title_full_unstemmed |
Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos |
title_sort |
investigating the impacts of climate, hydrology, and asian monsoon intensity on a 13 kyr speleothem record from laos |
publisher |
eScholarship, University of California |
publishDate |
2016 |
url |
http://www.escholarship.org/uc/item/1cp3q8j9 http://n2t.net/ark:/13030/m53n6qnb |
op_coverage |
185 |
geographic |
Greenland Indian Pacific |
geographic_facet |
Greenland Indian Pacific |
genre |
Greenland Greenland ice cores |
genre_facet |
Greenland Greenland ice cores |
op_source |
Yang, Hongying. (2016). Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos. UC Irvine: Earth System Science. Retrieved from: http://www.escholarship.org/uc/item/1cp3q8j9 |
op_relation |
http://www.escholarship.org/uc/item/1cp3q8j9 qt1cp3q8j9 http://n2t.net/ark:/13030/m53n6qnb |
op_rights |
public |
_version_ |
1766020353201537024 |