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基本组成部分，控制着世界各地的热量和降雨分布。然而，关于深水地层的长期可变性，或者它是否随着区域气候模式的变化而发生变化，人们知之甚少。该项目将在红海北部产生深海通风和表层气候条件的新记录，那里的现代深水形成可以作为更大规模全球过程的模型。这些记录将提供对过去几个世纪红海深水形成的时间变异性和控制机制的洞察。更好地了解海洋环流的长期可变性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可变性的模式和量化人为强迫对最近全球变化的贡献。增加我们对这种海洋变异性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生以及本科生和高中生提供培训和指导，并将通过每年数次向K-12课堂和普通公众介绍珊瑚礁科学的多媒体演示来支持外展。这项研究将利用表层海洋放射性碳(14C)测量重建红海北部深海混合和红海流出水(RSOW)形成的可变性。巨大的珊瑚在它们的骨骼中保存着海洋化学的记录，而来自红海最北部的长珊瑚钻芯是监测这一重要位置表面14C的理想位置。14C将在现有的每年条带的Porites lobata/LuTea珊瑚钻芯中从单个生长层的均质样本上进行测量，钻芯可以追溯到近230年前。低14C值将反映红海北部气旋环流的强度，并提供深层通风和14C耗尽的深水进入表层的记录。将对时间序列进行分析，以确定时间变率的模式，并将其与大规模区域或半球气候(如北极涛动)的指数进行比较，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，这是在极端冬季大气冷却之前为地表水的致密化和下沉“创造条件”的前提条件。

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.