Collaborative Research: Bioclimatic Reconstruction of the Past 50,000 Years from Eolian Sequences in the Westerlies-Dominated Central Asia

本研究旨在通过对多个厚风成剖面的多代理研究，重建以西风带为主的中亚地区近5万年的详细生物气候历史。西风带为主的地区包括准噶尔盆地（新疆西北部）和哈萨克斯坦丘陵平原（哈萨克斯坦东部），它们标志着东亚季风和西风带为主的“欧洲”气候系统之间的交汇处。这项调查将从一套跨越过去5万年的黄土/古土壤剖面中产生古气候代用记录。重建将采用地球物理、地球化学和地球生物相结合的方法。基于花粉、蜗牛、有机质碳-13和环境磁参数的生物气候传递函数将沿着三个N-S样带产生，以提供过去5万年生物气候变化的区域覆盖。从研究区风成序列中相对高分辨率地重建生物气候变化，将为理解过去5万年半球和全球尺度的强迫机制以及海洋-大气-大陆耦合提供背景。生物气候重建不仅有助于更好地理解东亚季风与西风带的相互作用历史，而且有助于更好地理解北大西洋涛动（NAO）与太平洋北美涛动（PNA）之间的遥相关关系。这项研究的结果将提高对陆地-空气耦合反馈机制的理解，并验证大气气溶胶流入可能引发全球大气CO2变化的假设。该项目将通过建立国际机构（美国、哈萨克斯坦和中国）之间的合作，增强全球气溶胶研究网络的合作可能性，重建的生物气候历史将为解决中亚地区人为加剧的荒漠化问题提供见解。

This study aims to reconstruct a detailed bioclimatic history of the last 50,000 years in the westerlies-dominated Central Asia based on a multi-proxy study of several thick eolian sections. The westerlies-dominated region includes the Dzungaria Basin (northwestern Xinjiang) and the Kazakhstan Hills and Plains (eastern Kazakhstan) that mark the conjunction between the East Asian Monsoon and the westerlies-dominated "European" climate systems. This investigation will produce paleoclimatic proxy records from a suite of loess/paleosol sections that span the past 50,000 years. A combination of geophysical, geochemical, and geobiological proxies will be used in the reconstruction. Bioclimatic transfer functions based on pollen, snails, carbon-13 of organic matter, and environmental magnetic parameters will be produced along three N-S transects to provide regional coverage of bioclimatic changes during the past 50,000 years. A relatively high-resolution reconstruction of bioclimatic changes from eolian sequences in the study area shall provide a context for understanding hemispheric- and global-scale forcing mechanisms and ocean-atmosphere-continent couplings throughout the past 50,000 years. The bioclimatic reconstruction will permit a better understanding of not only the interacting history between the East Asian monsoons and the westerlies but also the teleconnections between the North Atlantic Oscillation (NAO) and the Pacific North American (PNA) Oscillation. The outcomes of this research will improve understanding of the land-air coupled feedback mechanisms and validate the hypothesis that atmospheric aerosol influx might have triggered global atmospheric CO2 changes. This project will enhance partnership possibilities in a global network of aerosol studies by establishing collaborations among international institutions (U.S., Kazakhstan, and China) and the reconstructed bioclimatic history will provide insight for combating the ongoing problem of human-exacerbated desertification in Central Asia.