Inter-hemispheric Water Exchange in the Indian Ocean: Discovering the Red Sea Overflow Water Pathways and Variability

该项目将分析有关海洋温度和盐度的数据以及数值模型输出，以研究红海沃茨如何进入印度洋并通过印度洋传播。红海是全球最咸的沃茨之一。这些沃茨水域在500至1，500 m深处进入印度洋;它们沿着尚不清楚的路径传播，可以远至非洲南端以及澳大利亚西部海域。我们对红海海水扩散的了解有限，是因为在印度洋的观测历史稀少。直到最近15年，科学家才获得该地区的盐度和温度数据。这些数据将用于确定红海水团，并通过观察其与周围沃茨明显不同的温度和盐度特征，在整个海洋中追踪它们。该项目将有助于了解这种水流如何有助于将热量转移到海洋深处，这是一个影响地球气候的过程。研究结果将促进科学的进步，并通过可以改善气候预测的信息间接促进国民健康，繁荣和福利。红海溢流水（ROW）与出现在类似中间深度的较新鲜和较冷的印度尼西亚中层水（IIW）和南极中层水（AAIW）形成鲜明对比，使其成为中间深度环流的示踪剂。这种盐水也可能影响中间层的分层和动力学。拟议的研究将调查RSOW的路径，时间变化，并与其在印度洋的传播使用现场观测，数据同化模拟输出和粒子跟踪方法的物理机制。具体目标是：㈠确定印度洋大规模中间环流的特征，包括与季风有关的变化，并调查其与地面环流的联系; ㈡确定印度洋RSOW的路径，以了解它如何到达西澳大利亚以及是否到达南大西洋;（iii）调查与印度洋三个中间水团之间的RSOW扩展和锋面区有关的物理机制及其与环流的关系。该项目将导致利用新数据和现代方法定量描述RSOW的时空分布和印度洋的中间环流。目的是了解这种盐水的循环和潜在的影响，通过印度-大西洋水交换的全球翻转循环的作用。印度洋是全球海洋中研究最不足的区域之一，甚至其基本动力学仍在讨论中。这项工作将填补我们对印度洋环流的认识中的一些主要空白，印度洋环流与其他大型海洋盆地有着明显的不同。

This project will be analyzing data on ocean temperature and salinity, and numerical model outputs to examine how Red Sea waters enter and propagate through the Indian Ocean. The Red Sea produces one of the saltiest waters of the global oceans. These waters enter the Indian Ocean at depths 500 to 1,500 m; they spread along pathways that are not well understood and can travel as far as the southern tip of Africa, as well as off western Australia. Our limited understanding of Red Sea water spreading is because of the historical scarcity of observations in the Indian Ocean. It is only the last 15 years that salinity and temperature data from this region have become available to scientists. These data will be used to identify Red Sea water masses and trace them throughout the ocean by looking at their temperature and salinity characteristics that are significantly different than those of the surrounding waters. The project will contribute into understanding how such water flow contributes to the transfer of heat in to deeper parts of the ocean, a process that influences the Earth's climate. The study findings will promote the progress of science and, indirectly, will advance the national health, prosperity and welfare through information that could improve climate prediction. Red Sea Overflow Water (ROW) contrasts sharply with both the fresher and cooler Indonesian Intermediate Water (IIW) and the Antarctic Intermediate Water (AAIW) that occur at similar intermediate depths, making it a tracer for the intermediate- depth circulation. This saline water may also affect the stratification and dynamics of the intermediate layer. The proposed research will investigate the RSOW pathways, temporal variability, and the physical mechanisms associated with its spreading in the Indian Ocean using in situ observations, data-assimilated simulation outputs and a particle tracking method. The specific objectives are to: (i) Characterize the large-scale intermediate circulation of the Indian Ocean, including monsoonal-related variability, and investigate its connection to the surface circulation; (ii) determine the pathways of the RSOW in the Indian Ocean to understand how it reaches western Australia and whether it reaches the south Atlantic; (iii) investigate the physical mechanisms associated with the RSOW spreading and the frontal zones between the three intermediate water masses of the Indian Ocean and their relation to the circulation. The project will lead to the construction of a quantitative description of RSOW space-time distribution and the intermediate circulation of the Indian Ocean using new data and modern approaches. The aim is to understand the role of this saline water to the circulation and potential impacts on the global overturning circulation through the Indo-Atlantic water exchange. The Indian Ocean is one of the most understudied regions of the global oceans, and even its basic dynamics are still under discussion. This work will fill in some of the major gaps in our knowledge of the Indian Ocean circulation, which differs markedly from the other large ocean basins.