Collaborative Research: P2C2--Controls on Water Isotope Variability in the Tropical Pacific: A Strategy to Improve Paleoclimate Interpretations

过去热带降水的古气候重建依赖于根据过去降水的变化来解释氢和氧同位素的变化。该项目的目标是更好地了解热带太平洋降水对气候变化的反应，以及气候的季节和年际变化如何影响降水的稳定同位素组成。研究人员包括一名科学家和一名来自佐治亚理工学院的博士后研究员，以及一名来自科罗拉多大学的科学家。他们将从热带太平洋的四个岛屿位置收集和测量水蒸气、降雨和海水中稳定的氧和氢同位素。在PI执行现场程序期间，将在现场采集样本。抽样计划还将包括由当地个人进行全年抽样，他们将接受适当抽样技术的培训。采样战略包括对日循环进行超高分辨率采样，以及每天和更长时间的采样，以评估水同位素变异性与气候变化的关系，从分季节时间尺度到年际时间尺度和整个流域尺度。稳定的同位素数据将与国家大气研究中心的同位素气候模型相结合，以将高频同位素变化的气候机制与由此产生的代表降雨古气候指标重建的数据类型的较长期平均值联系起来。利用这种方法，PI希望提供更准确的古气候指标评估，以及更好地理解这些类型的重建中所包含的不确定性。最近，致力于测量和解释水稳定同位素的古气候出版物的数量增加，以及一些解释可能过于简单化，使得这一项目可能对古气候研究产生重大影响。该项目包括两名成熟的研究人员，Kim Cobb(佐治亚州)。技术。)和大卫·诺恩(CU)，但这个项目的主要推动者是佐治亚州EAR博士后研究员杰西卡·康罗伊。技术，由AGS古气候计划支持。该项目建立在PRF奖的基础上，提供更多进入太平洋进行采样的机会，与CU Noone合作获得NCAR GCM，并为博士后完成工作提供第三年的支持。

Paleoclimate reconstructions of past tropical precipitation rely on interpreting hydrogen and oxygen isotopic variations in terms of past changes in precipitation. This project has the goal of better understanding of the response of tropical Pacific precipitation to climatic variability and how the stable isotope composition of the rainfall is affected by seasonal and interannual changes in the climate. The researchers include a scientist and a postdoctoral fellow from Georgia Institute of Technology and a scientist from the University of Colorado. They will collect and measure the stable oxygen and hydrogen isotopes in water vapor, rainfall and seawater from four island locations in the tropical Pacific. Samples will be collected on site during field programs executed by the PIs. The sampling program will also include year-round sampling by local individuals who will be trained in proper sampling techniques. The sampling strategy includes ultra high-resolution sampling of the diurnal cycle, as well as daily and longer sampling in order to evaluate the relationship of water isotope variability to climate change from sub-seasonal to interannual time scales and on a basin wide scale. The stable isotope data will be integrated with an isotope-enabled climate model at the National Center for Atmospheric Research to link the climate mechanisms for the isotope variability at high frequency with the resulting longer term averaged values that typify the type of data reconstructed by paleoclimate proxies of rainfall. Using this approach, the PIs hope to provide a more accurate evaluation of paleoclimate proxies as well as a better understanding of the uncertainties embedded in these types of reconstructions.The recent rise in the number of paleoclimate publications dedicated to measuring and interpreting water stable isotopes, and the possibly oversimplified nature of some of the interpretations, makes this project likely to have a significant impact on paleoclimate research. The project includes two established researchers, Kim Cobb (GA. Tech.) and David Noone (CU), but the main driver of this project is Jessica Conroy, an EAR Postdoctoral Research Fellow at Ga. Tech., supported by the AGS Paleoclimate Program. This project builds on the PRF award by providing greater access to the Pacific for sampling, collaboration with Noone at CU for access to the NCAR GCMs, and a third year of support for the postdoc to complete the work.