Agulhas rings pathways and the resulting MOC control

智力优点：这项研究将提高对非线性气候过程的理解，因为它们与回射电流和涡流形成有关。特别是，涡流生成和海岸线倾斜，底部地形，上游位涡之间的关系将被检查。一个理论和数值模拟方法将被用来实现这些目标。这项研究的重点是一个关键的问题，子午翻转单元（MOC）：厄古拉斯环注入，迫使大量的盐进入南大西洋，因此是至关重要的维持大西洋相对较高的盐度。 最近对古海洋学代理的分析表明，与今天的注入水平相比，在新仙女木时期（当时MOC没有运行），咸的厄古拉斯环注入南大西洋的数量急剧减少。增加到今天的水平发生在新仙女木期结束时，有人认为，流入大西洋的盐量增加重新启动了当时崩溃的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，注入的变化是由于南非海岸线（相对于东西方向）在发生回折的位置倾斜。这种倾斜随纬度变化很大，“在大陆最南端附近几乎为零，在马达加斯加附近的低纬度地区接近90'。在这种情况下，在小倾斜情况下，环能够自由地传播远离生成区域，但在大倾斜情况下不能。这是因为沿岸迁移只是公海向西迁移乘以倾斜的余弦，因此在小倾斜情况下有显著的沿岸迁移分量，而在大倾斜情况下没有。 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的数值实验，以调查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到MOC，其功能对世界气候至关重要。拟议的研究与长期尺度上的海洋变化有关，因此对全球气候变化和可预测性这一重大社会问题很重要。一名博士毕业生。学生将在这个需要应届毕业生研究领域得到支持。该项目还将加强我们的外展计划，使在佛罗里达治安官青年牧场（FSYR）居住和接受教育的贫困儿童（男孩和女孩）接触科学。这些牧场里住着几百名贫困的女孩和男孩，佛罗里达治安官认为，除非远离他们的直接社会环境，搬到其他地方，否则他们有可能成为罪犯。塔拉哈西的联邦监狱也将开展类似的外联方案。

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.