Dynamical and Material Connectivity Across Continental Shelves

在碎波区内，水通常混合良好，因为波浪作用主导动力学并产生强烈的湍流。在大陆架的更远的近海，水按密度分层，环流主要由风和压力梯度驱动。这两种制度通常是分开研究，因为在动态和可变性的规模的巨大差异。然而，交换过程中的冲浪架过渡区（SSTZ）是至关重要的一些重要的问题，从幼虫运输污染。这项研究将开发和使用建模方法，处理这两套动态和规模优雅，并导致更好地了解这个重要的过渡区。主要的假设是：（1）SSTZ有很高的内在变化超出风，潮汐和波浪强迫流;（2）海浪涡旋和亚中尺度陆架涡旋有间歇性的强相互作用;（3）涡旋在设置跨和沿着水深梯度，以及垂直通过密度跃层的物质输送率中起着主导作用。这项研究计划是一个必要的先决条件，以解决许多重要的通量的海洋地球化学，生态，污染物和沉积通量内的SSTZ。该方法是使用多重嵌套环流模型（区域海洋模拟系统，ROMS），其中包括波平均斯托克斯漂移涡力和物质平流和波增强混合过程，耦合到表面重力波模型，其中包括多普勒频移折射电流。它将用于一系列理想化的海平面上升过渡区过程研究，以评估水深形状、分层、表面波、沿岸主流及其不稳定性、海浪涡流、陆架涡流和沿岸陷波、潮汐和暴雨水流入等因素的相互影响。此外，将在南加州的几个SSTZ站点进行长时间的真实ROMS模拟，包括完整的物理和积极的缩小尺度网格嵌套，现有的测量将提供模型验证测试。通过与日本和圣巴巴拉同事的无偿合作，真实的SSTZ建模和验证研究将扩展到其他地点。学术价值：冲浪涡旋和亚中尺度陆架涡旋都是相对未被探索的现象，拟议的对其性质、动力学和SSTZ中物质输运影响的全面理论和计算研究将导致新的现象学发现、未来的验证实地实验以及对这一前线人-海界面中物质通量的重新评估。近岸区域是人类活动与海洋的主要交叉点，在理解和模拟其海流、污染物、生态系统、洪水和海滩形态方面的进展将有助于更好地管理和保护。所获得的知识将通过专业和公共讲座和出版物传播;通过与国家气象局海滩安全预报员和加利福尼亚州橙子县废水管理人员协商;并纳入加州大学洛杉矶分校的本科生和研究生海洋课程。它将为少数STEM研究生提供研究培训。它的研究合作将加强与日本的国际科学合作以及圣巴巴拉海峡巨型海藻森林生态系统长期生态研究计划的物理海洋学基础。

Inside the surf zone, the water is typically well mixed because wave action dominates dynamics and creates strong turbulence. Further offshore on the continental shelf, the water is stratified by density and circulation is primarily driven by wind and by pressure gradients. These two regimes are typically studied separately because of the drastic differences in the dynamics and scales of variability. However, exchange processes at the Surf-Shelf Transition Zone (SSTZ) are critical for a number of important concerns ranging from larval transport to pollution. This study will develop and use modeling approaches that handle both sets of dynamics and scales gracefully and lead to a better understanding of this important transition zone. The primary hypotheses are (1) the SSTZ has high intrinsic variability beyond the wind-, tide- and wave-forced flows; (2) surf eddies and submesoscale shelf eddies have intermittent strong interactions; and (3) the eddies play a dominant role in setting the rates of material transport across and along bathymetric gradients, as well as vertically through the pycnocline. This research program is a necessary precursor to addressing the many important fluxes of biogeochemical, ecological, pollutant, and sedimentary fluxes within the SSTZ. The approach is to use a multiply-nested circulation model (Regional Oceanic Modeling System, ROMS) that includes the wave-averaged Stokes drift vortex force and material advection and wave-augmented mixing processes, coupled to a surface gravity wave model that includes Doppler-shift refraction by the current. It will be used for a set of idealized SSTZ process studies to assess the competing influences of bathymetric shape; stratification; surface waves; prevailing alongshore currents and their instability; surf eddies; shelf eddies and coastally-trapped waves; tides; and storm-water inflows. In addition, realistic ROMS simulations, with full physics and aggressive down-scale grid nesting, will be made for extensive periods at several SSTZ sites in Southern California, and existing measurements will provide model validation tests. Realistic SSTZ modeling and validation studies will be extended to other sites through unpaid collaborations with Japanese and Santa Barbara colleagues.Intellectual Merit :Both surf eddies and submesoscale shelf eddies are relatively unexplored phenomena, and the proposed comprehensive theoretical and computational examination of their nature, dynamics, and material transport effects in the SSTZ will lead to new phenomenological discoveries, future field experiments for validation, and reassessments of the material fluxes in this front-line human-ocean interface.Broader Impacts :The nearshore region is the primary intersection of human activities with the ocean, and progress in understanding and modeling its behavior for currents, pollutants, ecosystems, inundation, and beach morphology will empower better management and protection. The knowledge gained will be disseminated through professional and public lectures and publications; by consultation with National Weather Service beach safety forecasters and Orange County, CA, wastewater managers; and by inclusion into the undergraduate and graduate ocean curriculum at UCLA. It will provide research training for a minority STEM graduate student. Its research collaborations will strengthen both an international scientific cooperation with Japan and the physical oceanographic underpinnings of the Long Term Ecological Research program on the giant kelp forest ecosystem in the Santa Barbara Channel.