P2C2: Synthesis Study of the Tropical Rain Belt Through the Holocene

这个项目的动机是，热带雨带（TRB），包括海洋和大陆热带辐合带（ITCZ）和季节性季风系统，在地球气候中起着重要作用，并对社会、生态系统和全球气候产生强烈影响。在全新世期间，TRB的强迫变化被用来解释许多观测到的热带降雨的减少和增加。然而，驱动TRB动态变化的物理过程及其与气候强迫的关系尚不清楚。该奖项旨在通过利用广泛的热带古水文气候记录网络和新的同位素模式模拟来评估全新世TRB变化的驱动因素。本项目旨在：(1)评估TRB不同分量（海陆辐合和季节性季风）对全新世气候强迫函数和反馈的响应，包括生物地球物理反馈和与ENSO的相互作用；(2)将TRB的变化转化为代理记录器的变化，包括基于降水同位素比值的记录器的变化。该项目的科学目标将通过综合TRB位置和强度的气候代理记录以及NCAR的同位素支持群落地球系统模型（CESM）的一系列模型实验来实现。全新世不同阶段的时间片将为合成数据产品提供气候动力学背景。一系列敏感性实验将有助于确定生物圈-大气反馈和ENSO/TRB（厄尔尼诺-南方涛动）相互作用对同位素和非同位素代用物的影响程度。新兴代理系统模型的工具包将集成到CESM中，以便直接与代理记录网络进行比较。预计这项计划将有助于评估预计21世纪TRB的强迫变化。更广泛的影响包括升级和维护CESM的同位素版本，促进该机构博士后学者社区的发展，发展以发现为基础的本科教育经验，以及增加新的科学数据和分析，以帮助提高对自然气候变率的理解。

This project is motivated by the idea that the tropical rain belt (TRB), including the oceanic and continental Inter-tropical Convergence Zone (ITCZ) and seasonal monsoon systems, plays a fundamental role in the Earth's climate and strongly impacts societies, ecosystems, and global climate. During the Holocene, forced changes in the TRB have been invoked to explain many observed failures and increases in tropical rainfall. However, the physical processes driving changes in TRB dynamics and their relationship to climate forcings remain unclear.This award generally aims to evaluate the drivers of Holocene TRB variations by utilizing a wide network of tropical paleo-hydroclimate records and new isotope-enabled model simulations. This project aims to: (1) evaluate the response of the TRB's distinct components (convergence over ocean and land, and seasonal monsoons) to Holocene climate forcing functions and feedbacks, including biogeophysical feedbacks and interactions with ENSO; and (2) translate changes in the TRB into changes in proxy recorders, including those based on precipitation isotope ratios.The scientific objectives of this project will be achieved through a synthesis of climate proxy records of TRB position and intensity and a series of model experiments with NCAR's isotope-enabled Community Earth System Model (CESM). Time slices at different stages of the Holocene will provide a climate dynamical context for the synthesized data product. A set of sensitivity experiments will help determine the degree to which biosphere-atmosphere feedbacks and ENSO/TRB (El Nino-Southern Oscillation) interactions influence both isotopic and non-isotopic proxies. A toolkit of emerging proxy system models will be integrated into CESM to compare directly with the network of proxy records. It is expected that this project will help evaluate the forced changes in the TRB projected for the 21st century.The Broader Impacts include upgrading and maintaining the isotopic version of the CESM, enabling the development of a post-doctoral scholar community at the institution, developing discovery-based undergraduate educational experiences, and adding new scientific data and analyses to help improve the understanding of natural climate variability.