The role and response of the tropical Pacific thermocline in Plio-Pleistocene climate trends and obliquity cycles

热带太平洋温跃层在上更新世气候趋势和倾角循环中的作用和响应

• 批准号: 0623204
• 负责人: Steven Hovan
• 金额: --
• 依托单位: Indiana University of Pennsylvania Research Institute
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-10-01 至 2010-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0623204&HistoricalAwards=false
• 关键词: role; response; tropical; Pacific; thermocline

THE ROLE AND RESPONSE OF THE TROPICAL PACIFIC THERMOCLINE IN PLIO-PLEISTOCENE CLIMATE TRENDS AND OBLIQUITY CYCLESToday, the 'normal' mean state of the tropical Pacific is temporarily perturbed by short-lived El Nino events, which have global climate effects. However, there is growing evidence that the mean state has not been stable over long (geologic) timescales due to changes in sub-surface oceanic (thermocline) conditions, and that changes in the mean state have profound global climate effects that could explain the onset of the ice ages. The proposed study will focus on the last 5 Ma of earth history, which includes the early Pliocene warm period, the most recent period of sustained global warmth relative to today, and the global cooling that led to the ice ages. This project will test the hypotheses that 1) the early Pliocene warm period included El Nino-like mean conditions and the transition to cooler ice age climate was accompanied by a gradual shoaling of the thermocline and a switch from permanent 'El Nino-like' to modern 'normal' conditions and 2) higher frequency (41 kyr, glacial-interglacial) sea surface temperature (SST) variability in the tropical Pacific is related to changes in thermocline conditions. To address these hypotheses, we will analyze the elemental (Mg/Ca) and stable isotope composition of fossil foraminifera as well as organic biomarkers and sediment composition from deep sea sediments to reconstruct SST, precipitation, wind strength, and thermocline depth. This study will contribute to a fundamental understanding of the role of tropical Pacific processes in global climate change and will provide a data set for modelers to improve our interpretations and test their hierarchy of models. A graduate student and undergraduates will conduct research on this project. Research-based learning is encouraged for undergraduates. The PI's are involved with initiatives and/or established programs to increase student diversity and to expose high school students to cutting-edge science.

热带太平洋热跃层在Plio-pelyisce的气候趋势和倾斜环节中的作用和反应，热带太平洋的“正常”平均状态暂时受到具有全球气候影响的短暂寿命El Nino事件的扰动。 但是，越来越多的证据表明，由于地下海洋（热级线）条件的变化，平均状态在长期（地质）的时间尺度上不稳定，并且平均状态的变化具有深远的全球气候效应，可以解释冰年的开始。 拟议的研究将重点介绍地球历史的最后5 MA，其中包括上新世温暖时期，最近的全球持续温暖时期，以及导致冰河时代的全球冷却。 This project will test the hypotheses that 1) the early Pliocene warm period included El Nino-like mean conditions and the transition to cooler ice age climate was accompanied by a gradual shoaling of the thermocline and a switch from permanent 'El Nino-like' to modern 'normal' conditions and 2) higher frequency (41 kyr, glacial-interglacial) sea surface temperature (SST) variability in the tropical Pacific is related to changes in热跃层条件。为了解决这些假设，我们将分析化石有孔虫的元素（mg/ca）和稳定的同位素组成以及有机生物标志物以及从深海沉积物到重建SST，降水，风强度和热级线深度的沉积物组成。 这项研究将有助于对热带太平洋过程在全球气候变化中的作用的基本了解，并为建模者提供数据集，以改善我们的解释并测试其模型的层次结构。研究生和本科生将对该项目进行研究。鼓励基于研究的学习对于本科生。 PI参与了计划和/或已建立的计划，以增加学生的多样性并使高中生接触尖端科学。