Collaborative Research: Quantifying East African hydroclimate seasonal variability for humid intervals during the last 200 kyrs, Omo-Turkana Basin

拟议的项目将通过研究东非奥莫-图尔卡纳的样本来研究季风变化如何塑造生态系统。该项目将使用各种工具来检查季节性降雨量的变化，并测试季节性增加是否与雨季间隔密切相关。化石数据和化学分析将被用来了解过去的环境，并帮助确定这个敏感、水资源有限的地区将如何应对由人为气候变化塑造的现代和未来世界。国际合作将包括为下一代地球科学家提供培训机会，重点是支持来自美国和埃塞俄比亚的本科生。这两个PI主要以本科院校为基础，并将通过前期实地工作规划、协作性实地工作和定期项目团队会议来发展学习社区。该项目有可能从STEM历史上服务不足的社区招募、吸引和留住学生，继续成为地球科学领域的领导者。该项目将检验这样一种假设，即太阳辐射最大值增强了东非季风的强度，从而在潮湿时期增强了东非的季节性。了解极端的季节性对于限制陆地古气候，从而限制早期人类和现代人进化的东非的古环境条件和资源可获得性是至关重要的。具体地说，该项目将1)建立东非过去200年雨季期间的单阀介形虫碳和氧同位素替代记录，2)利用微量元素和介形虫古生态学编制基于介形虫的季节性替代记录，3)利用现代水同位素记录编制和校准过去200年关键时段的古水文气候模型。考虑到研究地点对热带辐合带(ITCZ)和步行者环流等重大大气现象的敏感性，这项研究的结果将提高对过去200年潮湿时段季节性程度的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The proposed project will examine the ways in which monsoon variability shapes ecosystems by studying samples from Omo-Turkana in eastern Africa. This project will use a variety of tools to examine seasonal rainfall variability and test whether increased seasonality is strongly correlated with wet intervals. Fossil data and chemical analyses will be used to understand past environments and help determine how this sensitive, water-limited region will respond to a modern and future world shaped by anthropogenic climate change. International collaboration will include training opportunities for the next generation of geoscientists, with a focus on supporting undergraduates from both the US and Ethiopia. Both PIs are based at Primarily Undergraduate Institutions and will develop a learning community through pre-fieldwork programming, collaborative fieldwork, and regular project team meetings. The project has the potential to recruit, engage and retain students from historically underserved communities in STEM to continue as leaders in the geosciences. This project will test the hypothesis that solar insolation maxima increased the strength of the East African monsoon, resulting in enhanced seasonality in eastern Africa during humid periods. Understanding the extremes of seasonality is essential to constrain the terrestrial paleoclimatic and thus paleoenvironmental conditions and resource availability in eastern Africa where early hominins and modern humans evolved. Specifically, the project will 1) establish a single valve ostracod carbon and oxygen isotope proxy record of the eastern African seasonality during wet phases over the last 200 kyrs, 2) develop complementary ostracod-based proxy records of seasonality using trace elements and ostracod-paleoecology, and 3) use modern water isotope records to develop and calibrate a model of paleo-hydroclimate for key intervals over the past 200 kyrs. Given the sensitivity of the study site to significant atmospheric phenomena such as the Intertropical Convergence Zone (ITCZ) and walker circulation, the outcome of this study will improve understanding of the degree of seasonality in humid intervals over the last 200 kyrs.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.