Controls on Deep Water Ventilation and Red Sea Overflow Water Formation in the Red Sea

深海环流是全球气候系统的一个基本组成部分，控制着世界各地热量和降雨的分布。 然而，人们对深水地层的长期变化性或它是否作为区域气候模式的函数发生变化知之甚少。 该项目将在红海北部创造深海通风和表面气候条件的新记录，现代深水地层可以作为更大规模全球过程的模型。 这些记录将有助于深入了解过去几个世纪控制红海深水形成的时间变化和机制。更好地了解海洋环流的长期变率对于了解气候系统如何运作至关重要，特别是对于确定自然背景变率的模式和量化人为强迫对近期全球变化的贡献。 增加我们对这种海洋变化如何与大规模气候振荡联系在一起的知识，可能使我们能够预测未来的变化，并可能减轻其对社会的影响。 该项目将为一名博士提供培训和指导。本研究将利用表层海洋放射性碳（14 C）测量数据，重建深海混合和红海流出水（RSOW）形成在北方红海的变化。 巨大的珊瑚在它们的骨骼中保存着海洋化学的记录，而来自红海北方的长珊瑚钻芯是监测这一重要地点表面14 C的理想地点。 14 C将测量从现有的年度带状滨珊瑚lobata/lutea珊瑚钻芯延伸到近230年的各个生长层的均质化样品。 低14 C值将反映北方红海气旋环流的强度，并提供深层通风和14 C耗尽的深层水混合到表层的记录。 将对时间序列进行分析，以确定时间变化的模式，并将其与大规模区域或半球气候指数（如北极涛动）进行比较，以检验这样的假设，即这种气候模式通过对气旋环流和深层混合的影响来控制RSOW的形成，而气旋环流和深层混合是在冬季大气极端冷却之前使地表沃茨致密化和下沉的“先决条件”。

Deep ocean circulation is a fundamental component of the global climate system, controlling the distribution of heat and rainfall around the world. However, little is known about the long-term variability of deepwater formation, or whether it has changed as a function of regional climate patterns. This project will generate new records of deep ocean ventilation and surface climate conditions in the northen Red Sea, where modern deepwater formation can serve as a model for larger-scale global processes. These records will provide insight into the temporal variability and mechanisms controlling Red Sea deepwater formation over the past few centuries. A better understanding of long-term variability in ocean circulation is critical to understanding how the climate system operates, especially for identifying patterns of natural background variability and quantifying the contribution of anthropogenic forcing to recent global changes. Increasing our knowledge of how such ocean variability may be linked to large-scale climate oscillations may enable us to predict future changes and potentially mitigate their impacts on society. This project will provide training and mentorship for one Ph.D. student as well as undergraduate and high school guest students, and will support outreach through multimedia presentations of coral reef science to K-12 classrooms and the general public several times each year.This research will reconstruct variability in deep ocean mixing and Red Sea Outflow Water (RSOW) formation in the northern Red Sea using surface ocean radiocarbon (14C) measurements. Massive corals preserve records of ocean chemistry in their skeletons, and long coral drill cores from the far northern Red Sea are ideally situated to monitor surface 14C in this important location. 14C will be measured on homogenized samples from individual growth layers in an existing annually-banded Porites lobata/lutea coral drill core extending back nearly 230 years. Low 14C values will reflect the strength of the cyclonic gyre circulation in the northern Red Sea, and provide a record of deep ventilation and the mixing of 14C-depleted deep water into the surface layer. The time series will be analyzed to identify patterns of temporal variability and will be compared to indices of large-scale regional or hemispheric climate (such as the Arctic Oscillation) to test the hypothesis that such climate patterns control the formation of RSOW, through the influence on cyclonic gyre circulation and deep mixing, which "preconditions" surface waters for densification and sinking prior to extreme winter atmospheric cooling.