Collaborative Research: What do global surface drifters tell us about submesoscale processes?

该奖项是根据2009年《美国复苏和再投资法》(公法111-5)资助的。最近对地表环路(具有明确旋转感的漂移轨迹)的全球普查揭示了亚中尺度(R15公里；Griffa，Lumpkin和Venziani 2008)尺度上结构分布的一些意想不到的特征。出现了三个主要区域：a)位于北纬10度和20度的盛行气旋性纬向带；b)位于30度和40度的盛行反气旋性纬向带；c)与大环形成区对应的缺乏亚中尺度存在的区域。这种分布背后的动力机制目前还不完全清楚，原因之一是小环路可能是不同过程的特征，例如亚中尺度涡旋和亚惯性Ekman响应。本研究侧重于亚中尺度分量，并研究了这些发现对开放海洋亚中尺度分布的影响。要解决的问题是：在世界海洋中，次中尺度过程的特征是极性和丰度方面的非平凡分布，是否受到它们形成的环境大尺度动力机制的调制？这个问题不能仅用拉格朗日资料来研究，而且其他全球数据集或全球数值模式没有足够的空间和时间分辨率来求解亚中尺度结构。因此，将使用漂流者建议的关键选定地区的极高分辨率(高达300米)区域模式来研究欧拉和拉格朗日动力学。这将得到区域模拟结果所示的理想化配置中的具体进程研究的补充。总体结果将是加深对公海次中尺度过程的性质和分布的了解。拟议的研究具有社会影响，因为它有助于理解上层海洋的气候和生物过程。结果将在UCSC和RSMAS的研究生班上公布，它们将成为推广计划的一部分。为ROMS模型模拟开发的分析算法将通过WikiROMS网页免费分发给更大的科学界。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).A recent global census of surface loopers (drifter trajectories with a definite sense of rotation) has revealed some unexpected features of the distribution of structures at scales of the submesoscale (R15 km; Griffa, Lumpkin, and Veneziani 2008). Three main regimes have emerged: a) a prevalently cyclonic zonal band at 10−20 degrees latitude; b) a prevalently anticyclonic zonal band at 30−40 degrees and c) regions devoid of submesoscale presence corresponding to areas of formation of great rings. The dynamical mechanisms behind this distribution are not completely understood yet, one of the reasons being that small loopers can be the signature of different processes, such as submesoscale eddies and subinertial Ekman response.This study focuses on the submesoscale component, and investigates the implications of the findings for submesoscale distribution in the open ocean. The question to be addressed is: Are submesoscale processes in the world ocean characterized by a nontrivial distribution in terms of polarity and abundance, modulated by the ambient large-scale dynamical regimes in which they form? This question cannot be investigated by means of Lagrangian data alone, and other global data sets or global numerical models do not have sufficient spatial and temporal resolution to solve submesoscale structures. Therefore very high resolution (up to 300 m) regional models of key selected areas suggested by the drifters will be used to investigate the Eulerian and Lagrangian dynamics. This will be complemented by specific process studies in idealized configurations indicated by the regional modeling results. The overall result will be an increased understanding of the properties and distribution of open ocean submesoscale processes.The proposed research has a societal impact because it contributes to the understanding of climate and biological processes in the upper ocean. The results will be presented in graduate classes at UCSC and RSMAS, and they will be part of outreach programs. Analysis algorithms developed for the ROMS model simulations will be freely distributed to the greater scientific community through the WikiROMS web-pages.