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首页> 外文学位 >Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos.
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Investigating the Impacts of Climate, Hydrology, and Asian Monsoon Intensity on a 13 kyr Speleothem Record from Laos.

机译：研究气候，水文和亚洲季风强度对老挝13年来Speleothem记录的影响。

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摘要

I present a high- resolution record of Southeast Asian Monsoon (SEAM) evolution compiled from delta18O 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 delta18O 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 delta 18O 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 delta 18O pattern, despite a 1.2‰ between sample delta18 O 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 delta18O 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 delta18 Op at four cave locations along the Asian monsoon region. Results show that delta18Op at the four cave sites reflects large-scale ocean-atmosphere processes, instead of local precipitation amount. Spatial correlation with vertical wind shear indicates that delta18Op 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 Nino events influence precipitation delta18O in Oman and northern Laos, in particular.
机译：我提供了高分辨率的东南亚季风（SEAM）演变记录，该记录是根据对老挝北部Tham Mai Cave的五个U-Th年代斑潜卵期（20.75N，102.65E）进行的delta18O测量结果汇编而来的，该位置是该区域之间的重要交汇处。印度和东亚季风系统。蛇麻草的氧同位素记录与可靠的铀系列日期有关，并表明记录范围为0.79至13 kyr BP，具有近十年的分辨率。在全新世期间，Tham Mai speleothem delta18O记录的特征是在全新世早期至中期较低的值，而在全新世晚期则值增加。这与整个亚洲季风地区看到的趋势相似，反映了对季风强度和ITCZ位置的强烈日照控制。 Younger Dryas的特征是δ18O突然增加，并且与年龄不定的中国speleothem记录和格陵兰冰芯中的平均偶数同步。这表明SEAM与高纬度突然降温事件同步减弱。; Tham Mai洞穴的四个蛇鞘从BP的4,300年同时增长到9,000 BP。尽管观察到样品delta18 O的变异性为1.2‰，这四个样品显示了相似的delta 18O模式。集总参数正演模型方法（KarstFor模型）用于评估这种1.2‰的差异在多大程度上可归因于水文变异性。结果表明，这个1.2‰的差异可能是由于一个洞穴内的水文变异而产生的;为了更好地解释亚洲季风区高分辨率氧同位素记录中的年际delta18O变异性，我利用了由频谱微动的启用同位素的一般方法获得的现有模拟结果循环模型（IsoGSM），以研究亚洲季风区四个洞穴位置delta18 Op的气候控制。结果表明，四个洞穴位置的delta18Op反映了大规模的海洋-大气过程，而不是局部的降水量。与垂直风切变的空间相关性表明，所有位置的delta18Op与季风强度和沃克环流显着相关。与SST和降水的空间相关性表明，ENSO可能确实发挥了作用，而且太平洋中部的厄尔尼诺现象影响了阿曼和老挝北部的降水del18O。

著录项

  • 作者

    Yang, Hongying.;

  • 作者单位

    University of California, Irvine.;

  • 授予单位 University of California, Irvine.;
  • 学科 Paleoclimate science.;Atmospheric sciences.;Geochemistry.
  • 学位 Ph.D.
  • 年度 2016
  • 页码 185 p.
  • 总页数 185
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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