Dynamical and Material Connectivity Across Continental Shelves

在冲浪区内，由于波浪作用主导了动力学并产生了强烈的湍流，所以水通常混合得很好。在离海岸更远的大陆架上，水因密度而分层，环流主要由风和压力梯度驱动。这两种情况通常是分开研究的，因为它们在变化的动力和尺度上存在巨大差异。然而，在冲浪架过渡区（SSTZ）的交换过程对于从幼虫运输到污染等一系列重要问题至关重要。本研究将开发和使用建模方法来优雅地处理两组动态和尺度，并更好地理解这一重要的过渡区。主要的假设是：(1)海表区在风、潮、波强迫流之外具有较高的内在变异性；(2)冲浪涡旋与亚中尺度陆架涡旋具有间歇性强相互作用；(3)涡旋在确定物质穿越和沿水深梯度以及垂直通过斜斜的输运速率方面起主导作用。该研究项目是研究海区生物地球化学通量、生态通量、污染物通量和沉积通量等重要通量的必要先导。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旋力、物质平流和波增强混合过程，再加上表面重力波模型，其中包括水流的多普勒偏移折射。它将用于一套理想化的SSTZ过程研究，以评估水深形状的竞争影响；分层;表面波;盛行的沿岸潮流及其不稳定性；冲浪涡流;大陆架涡流和海岸困波；潮汐;还有雨水流入。此外，现实的ROMS模拟，具有完整的物理和积极的小尺度网格嵌套，将在南加州的几个SSTZ站点进行长时间的模拟，现有的测量将提供模型验证测试。现实的SSTZ建模和验证研究将通过与日本和圣巴巴拉同事的无偿合作扩展到其他站点。学术价值：冲浪涡流和亚中尺度陆架涡流都是相对未被探索的现象，对它们的性质、动力学和物质在SSTZ的传输效应提出的综合理论和计算检查将导致新的现象学发现，未来的实地实验验证，并重新评估这一前沿人类-海洋界面的物质通量。更广泛的影响：近岸地区是人类活动与海洋的主要交叉点，在理解和模拟其对洋流、污染物、生态系统、洪水和海滩形态的行为方面取得的进展将有助于更好的管理和保护。所获得的知识将通过专业和公开讲座和出版物传播；通过与国家气象局海滩安全预报员和加利福尼亚州奥兰治县的废水管理人员协商；并将其纳入加州大学洛杉矶分校的本科和研究生海洋课程。它将为少数族裔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，并为圣巴巴拉海峡巨型海带森林生态系统的长期生态研究计划提供物理海洋学基础。

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.