Agulhas rings pathways and the resulting MOC control

智力价值：这项研究将提高对非线性气候过程的理解，因为它们与反射电流和涡流形成有关。特别地，涡旋的产生与海岸线倾斜、海底地形和上游位涡之间的关系将被研究。理论和数值模拟方法将用于实现这些目标。该研究的重点是一个对经向翻转细胞（MOC）至关重要的问题：阿古拉斯环注入迫使大量盐进入南大西洋，因此对维持大西洋相对较高的盐度至关重要。最近对古海洋学代用物的分析表明，在新仙女木时期（MOC未运行时），含盐的阿古拉斯环注入南大西洋的水平与今天的注入水平相比急剧减少。上升到今天的水平发生在新仙女木期末期，有人认为，与此相关的盐流入大西洋的增加重新启动了当时已经崩溃的MOC。考虑到环注入大西洋的盐异常目前大约是地中海和白令海峡的五倍，上述MOC重启的想法似乎是合理的。据推测，注入的可变性是由于南非海岸线的倾斜（相对于东西方向）在反射发生的位置造成的。这种倾斜度随纬度变化很大，在大陆最南端几乎为零，在马达加斯加附近的低纬度地区接近90度。在这种情况下，在小倾斜情况下，环能够自由地从产生区传播出去，而在大倾斜情况下则不能。这是因为长岸迁移只是向西的公海迁移乘以斜度的余弦，所以在小斜度的情况下有明显的长岸迁移成分，而在大斜度的情况下没有。该方法将采用非线性分析方法以及面向过程的研究和高分辨率数值实验来研究与上述问题的各种配置相关的过程。更广泛的影响：印度洋-大西洋海盆交换影响着MOC， MOC的功能对世界气候至关重要。拟议的研究与长时间尺度的海洋变化有关，因此对全球气候变化和可预测性的重大社会问题很重要。在需要新毕业生的研究领域，将支持一名研究生博士研究生。该项目还将加强我们的外展计划，让在佛罗里达警长青年牧场（FSYR）居住和接受教育的贫困儿童（男孩和女孩）接触科学。这些农场里住着几百名贫困的男孩和女孩，佛罗里达州的治安官认为，如果不让他们离开自己的社会环境，把他们安置在其他地方，他们就有可能成为犯罪分子。塔拉哈西的联邦监狱也将开展类似的外展项目。

Intellectual merit: The study will improve the understanding of nonlinear climatic processes as they relate to retroflecting currents and eddy formation. In particular, the relationship between eddy generation and coastline inclination, bottom topography, and upstream potential vorticity will be examined. A theoretical and numerical modeling approached will be used to achieve those goals.The study focus on a problem critical to the Meridional Overturning Cell (MOC): Agulhas rings injection that forces large amounts of salt into the South Atlantic and is thus critical for maintaining the Atlantic relatively high salinity. A recent analysis of paleoceanographic proxies reveals that the injection of salty Agulhas rings into the South Atlantic during the Younger Dryas (when the MOC was not operational) was dramatically reduced compared to today's injection levels. The increase to today's levels occurred toward the end of the Younger Dryas and it has been suggested that the associated increase in salt influx into the Atlantic re-started the, then-collapsed, MOC. Given that the salt anomaly that the rings inject into the Atlantic is presently roughly five times that of the Mediterranean Sea and the Bering Strait, the above MOC restart idea appears plausible. It has been hypothesized that the injection variability is due to the slanting of the South African coastline (relative to the east-west direction) at the location where the retroflection occurs. This slanting varies widely with latitude"it is almost zero near the southernmost edge of the continent and nearly 90' at lower latitudes off Madagascar. In this scenario, the rings are able to propagate freely away from the generation area in the small slant case but not in the large slant case. This is because the long-shore migration is just the open-ocean westward migration times the cosine of the slant so that there is a significant long-shore migration component in the small slant case but not in the large slant case. The approach will be to employ nonlinear analytical methods as well as process oriented studies and high-resolution numerical experiments to investigate processes associated with various configurations of the above problems. Broader Impacts: The Indian-Atlantic ocean basin exchange affects the MOC whose functioning is critical to the world climate. The proposed studies are pertinent to ocean variability on long time scales, and are thus important to the significant societal question of global climate change and predictability. One graduate Ph.D. student will be supported in this research area where new graduates are needed. The project will also enhance our outreach program of exposing underprivileged kids (boys and girls) housed and educated in the Florida Sheriffs Youths Ranches (FSYR) to science. These ranches house several hundred underprivileged girls and boys, identified by the Florida sheriffs to have a potential criminal future unless steered away from their immediate social environment and housed elsewhere. A similar outreach program will be conducted at the Federal prison in Tallahassee.