Collaborative Research: P2C2--Calibrating South East Asian Proxies: Speleothems and Tree-Rings

该项目涉及对老挝人民民主共和国北部和南部两个地点的洞穴和树木年轮进行交叉校准，这些地点的地理位置独特，以解决热带古气候学的基本问题。这些基本问题包括：厄尔尼诺-南方涛动(ENSO)和热带辐合带(ITCZ)在影响东南亚气候变异性方面的相对作用和相互关系是什么？目前，对于这些现象的档案如何反映气候，特别是每个档案的物理或生态生理控制如何影响从它们提取的稳定同位素记录，还没有一致的理解。研究小组旨在通过解决以下问题来更好地理解控制大气和陆地表面气候信号向气候代用品传输的过程：1)温度、降水和稳定同位素变化是如何记录在每个档案的物理、化学和生物特征中的？2)洞穴和树木年轮之间的局部和区域气候信号是同步的吗？3)固有的气候信号是否表现出带有季节偏差的代理间变异性，或者是低频率变异性与高频变异性，如果是，为什么？这项研究的具体目标包括：i)通过在老挝两个地点进行成对的洞穴和树木现代校准研究，探索热带洞穴和树木年轮之间的主要控制和相互关系；ii)通过代理系统建模以及将新的和现有的记录与仪器气候数据和模拟的降水三角洲18氧进行比较，检查仪器时期对洞穴和树木年轮稳定同位素记录的主要控制；以及iii)利用从老挝北部和南部收集的新的和以前收集的洞穴和树木岩心，将古气候记录追溯到上一个千年。在研究方面，该项目旨在解决不断演变的争议领域的各个方面，将气候档案和气候事件中的气候指标整合在一起。在辅导方面，该项目支持研究生在学年期间和本科生在曼哈顿科学和数学中心进行暑期研究。学生将协助进行实地考察、数据处理和分析、共同撰写论文和展示结果。其中一个合作机构威廉·帕特森大学(William Patterson University)是一所拉美裔服务机构，主要是一所教学大学，学生群体多样化，其中包括许多代表不足的少数族裔，他们是进入大学的第一代人。外展是由所有合作者进行的。其中一名首席研究员是一名美国原住民女科学家，她组织了美国印第安人地球系统科学夏季研究所，这是一个为期两周的高中生住宿项目。另一位首席研究员在越南组织了一年一度的国际生态田野学校。

This project involves a cross-calibration of speleothems and tree rings at two locations in northern and southern Lao PDR at locations uniquely situated to address fundamental questions in tropical paleoclimatology. Such fundamental questions include: What are the relative roles of, and inter-relationships between, the El Nino-Southern Oscillation (ENSO) and the Intertropical Convergence Zone (ITCZ) in influencing Southeast Asian climate variability? Currently, there is no coherent understanding of how the archives from these phenomena reflect climate, specifically how the physical or eco-physiological controls of each influence the stable isotope records extracted from them.The research team aims to better understand the processes that control the transfer of atmospheric and land surface climate signals to climate proxies by addressing the following questions: 1) How are temperature, precipitation, and stable isotopic variations recorded in the physical, chemical, and biologic signatures of each archive? 2) Are local and regional climate signals synchronous between speleothems and tree rings? and 3) Do the inherent climate signals exhibit inter-proxy variability with seasonal bias or low vs. high frequency variability, and if so, why? The specific objectives of the research include: i) exploring the dominant controls on and interrelationships between tropical speleothems and tree-rings through a paired cave and tree modern calibration study at two sites in Laos; ii) examining the dominant controls on speleothem and tree-ring stable isotope records for the instrumental period through proxy system modeling and comparison of new and existing records with instrumental climate data and modeled precipitation delta 18 Oxygen; and iii) extending the paleoclimate record back through the last millennium utilizing new and previously collected speleothems and tree cores from North and South Laos.The potential broader impacts cover three specific areas: research, mentorship, outreach. On the research side, the project aims to tackle aspects of evolving areas of controversy integrating climate proxies across climate archives and climatic events. In terms of mentoring, the project supports graduate students during the academic year and undergraduate students in summer research in the Manhattan Center for Science and Mathematics. Students will assist with fieldwork, data processing and analysis, co-authorship of papers, and presentations of results. One of the collaborative institutions, William Patterson University, a Hispanic Serving Institution, is largely a teaching university with a diverse student body that includes many underrepresented minorities that are first generation to college. Outreach is conducted by all the Collaborators. One of the Principal Investigators is a female Native American scientist and organizes the American Indian Summer Institute in Earth System Science, a two-week residential program for high school students. Another Principal Investigator organizes an annual international Ecological Field School in Vietnam.