P2C2: Seasonal Dynamics of the Indo-Asian Monsoon during Deglaciations

该项目旨在更好地限制在最后一个和倒数第二个冰期结束时气候过渡期间印度支那季风降雨和相关的大气动力学(例如急流)的季节行为。研究人员将使用最近开发的离子微探针分析方法来测量季节性分辨率下记录在洞穴中方解石矿物结构中的氧同位素比率(Delta18-氧)。随着洞穴的生长，记录了过去降雨量、来源和季节性的变化，生成了跨越数万到数十万年的过去降雨量变化的记录。对过去降水变化的研究很重要，因为它们可能为气候过渡期间降雨的基本控制和潜在反应提供有价值的洞察。研究小组将分析也门和以色列的洞穴，以补充来自东北部中国的季节性分辨率分析。这些样本代表了亚洲大气环流的一个组成部分，每个样本都有一个重要的季节性组成部分：西风带(以色列)、印度季风(也门)和东亚季风(中国)。此外，该小组将使用降雨增量18-氧气的全球气候模型模拟(即，共同体气候系统模型第3版，TRACE-21K共同体大气模型第3版)，以评估在过去两个冰期之后的关键气候时期，模拟的亚洲各地季节性降雨模式与观测到的降雨模式之间的一致性程度。该团队将对这两个时期的七个诊断时间片进行建模，当时季风降雨发生了重大变化，包括大约11500年前的一次变暖事件，当时可能发生了突然的十年尺度变化。更广泛的影响包括支持两名早期职业科学家进行研究，这可能有助于提高对时间和季风降雨的理解。这些影响还包括参与威斯康星大学麦迪逊地质博物馆的外展项目。

This projects aims to better constrain the seasonal behavior of Indo-Asian monsoon rainfall and related atmospheric dynamics (e.g. the jet stream) during climate transitions at the end of both the last and penultimate ice ages. The researchers will use recently developed methods for ion microprobe analysis to measure oxygen isotope ratios (delta18-Oxygen) recorded in the calcite mineral structure of speleothems at seasonal resolution. The speleothem delta18-Oxygen values record changes in past rainfall amount, source, and seasonality that are preserved as the speleothem grows, generating a record of past rainfall changes that can span tens to hundreds of thousands of years. Studies of past changes in precipitation are important because they potentially provide valuable insight on the fundamental controls and potential response of rainfall during climate transitions.The research team will analyze speleothems from Yemen and Israel to complement seasonal-resolution analyses from northeastern China. These samples represent a component of atmospheric circulation over Asia, each with an important seasonal component: the Westerlies (Israel), Indian Monsoon (Yemen), and East Asian Monsoon (China). Additionally, the team will to use global climate model simulations (i.e., Community Climate System Model version 3, TraCE-21K Community Atmosphere Model version 3) of rainfall delta18-Oxygen to assess the level of coherence between modeled and observed seasonal rainfall patterns across Asia during key climatic periods that followed the last two ice ages. The team will model a suite of seven diagnostic time-slices from these two periods when large changes in monsoon rainfall, including during a warming event ~11,500 years ago when an abrupt decadal-scale change may have occurred.The Broader Impacts involve supporting two early career scientists in research that could help improve the understanding of the timing and monsoonal rainfall. The Impacts also include participating in outreach programs with the UW-Madison Geology Museum.