SGER: Generation of Eddies by Oceanic Islands: A Laboratory Study

摘要：几十年来，在一些海洋岛屿附近观测到了中尺度涡旋。这些漩涡被怀疑是生物生产增强的区域。据推测，漩涡是由流过岛屿的水流在足够强的情况下产生的。对于一些有高山的岛屿，人们假设被岛屿偏转的风可以通过岛屿背风处的埃克曼泵产生漩涡。然而，虽然有对涡旋的观测，但对涡旋的产生机制及其初始演化尚未有全面的研究。在这个项目中，将进行一系列围绕圆柱体（代表一个岛屿）的流体流动的实验室实验。此外，在一些实验中，将对流体施加空间变化的应力。这两组实验代表了岛屿背风处两种可能的涡流形成机制。表面附近的三维速度将用粒子图像测速法确定。这些数据将使我们能够研究涡旋产生的动力学，以及涡旋平流远离圆柱体时的初始演化。将研究对一系列岛屿直径和分层的响应。更广泛的影响：该项目将提高我们对海洋中尺度和亚中尺度动力学的理解，并可能解决一些与岛屿涡形成及其对生物生产力的影响有关的流行假设。将与西班牙研究涡流对加那利群岛周围生态系统动态影响的科学家建立密切合作关系。还将与有兴趣研究岛屿产生涡流的建模者合作。

Abstract OCE-0723769Intellectual Merit: For many decades, mesoscale eddies have been observed near some oceanic islands. These eddies have been regions of suspected enhanced biological production. It has been speculated that the eddies are generated by the current flowing past the island when the current is sufficiently strong. For some islands which have tall mountains, it has been postulated t hat the winds deflected by the island can produce the eddies through Ekman pumping in the lee of the island. However, while there have been observations of the eddies, there has not been a comprehensive study to examine the generation mechanism of the eddies and their initial evolution. In this project, a series of laboratory experiments of fluid flow around a cylinder (representing an island) will be undertaken. In addition, a spatially varying stress will be applied to the fluid in some of the experiments. These two sets of experiments represent the two possible eddy formation mechanisms in the lee of an island. The three-dimensional velocity near the surface will be determined using particle image velocimetry. These data will allow us to examine the dynamics of the generation of the eddies and their initial evolution as the eddies are advected away from the cylinder. The response to a range of island diameters and stratification will be investigated.Broader Impacts:This project will improve our understanding of mesoscale and submesoscale dynamics of the ocean and will likely resolve some of the prevailing hypotheses related to eddy formation by islands and their influence on biological productivity. A close collaboration with scientists in Spain who have studied the influence of eddies on the ecosystem dynamics around the Canary Islands will be established. Collaborations with modelers interested in studying the generation of eddies by islands will also be pursued.