Collaborative Research: Developing Records of Hydroclimate Variability in the Southeastern United States from the Middle Holocene to Present-Day

美国东南部是重要的农业区，但近期发生的洪灾和旱灾已造成数十亿美元的经济损失。对于是什么驱动了降水-蒸发(水气候)趋势的变化，人们缺乏了解，部分原因是与美国其他地区相比，该地区的古气候记录较少。该项目将从四个湖泊收集沉积物岩心，其中两个位于佐治亚州和阿拉巴马州北部，两个位于南部。预计这些地区将做出不同的反应，这取决于主要控制水气候的因素。该项目将确定这些湖泊是否有适合于进一步深入研究过去5000年的记录，并最终能够确定什么是对水气候的重要控制以及它是如何随时间变化的。该项目的中心假设是，从公元4000年起，美国东南部的水气候主要受太平洋-北美模式控制，在选定的研究地点表现为降水偶极子。该项目将重点关注：1)从沉积中心和横断面岩心收集的沉积物序列的年代测定，2)确定沉积物堆积是否足以验证这一假设，以及3)记录收集到的岩心中的地层序列。沉积物中的物理(颗粒大小)、地球化学(碳和氮)和生物(花粉)参数的初步工作也将确定继续进行进一步研究的可行性。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 Southeastern United States is an important agricultural region, but recent flooding and drought events have caused billions of dollars in economic loss. There is a lack of understanding about what drives changes in precipitation-evaporation (hydroclimate) trends, in part because there are fewer paleoclimate records from this region compared to the rest of the United States. This project will collect sediment cores from four lakes, two in northern Georgia and Alabama and two in the south. These regions are expected to respond differently depending on what predominantly controls hydroclimate. This project will establish if these lakes have records that are suitable for further, in-depth study of the past 5000 years and can ultimately identify what is an important control of hydroclimate and how it changed through time.This project’s central hypothesis is that from 4000 years BP onwards, hydroclimate in the Southeastern United States has been predominantly controlled by the Pacific North American pattern which manifests as a precipitation dipole at the selected study sites. This project will focus attention on: 1) dating the collected sediment sequences from depocenter and transect cores, 2) establishing whether sediment accumulation is sufficient enough to test the hypothesis, and 3) documenting the stratigraphic sequences in the collected cores. Preliminary work on physical (grain size), geochemical (carbon and nitrogen), and biological (pollen) parameters in the sediments will also establish the feasibility of pursuing additional study.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.