OCE-PRF Track 1 (Broadening Participation): Internal wave-generated turbulent mixing and vertical nitrate flux during spring and neap tides along the Mid-Atlantic Bight shelf break

海洋生物碳泵将二氧化碳转化为有机碳，并将其从表层海洋输送到深渊。海洋的生物生产力取决于深海营养物质向上混合到海洋表面的速度。潮汐被认为有助于沿海海洋的这种混合，但我们不知道它们对生物碳泵的影响程度。在这个项目中，研究员将解决一个基本问题：潮汐是否会通过增加必需营养物质进入阳光照射的表层海洋的速度，显著影响沿海海洋的生物生产和有机碳出口？此外，该研究员将扩大代表性不足群体对海洋科学的参与，具体做法是领导实践教育活动，向巴尔的摩市公立学校的学生讲授机器人入门知识;在霍恩波因特实验室开放日期间向当地社区介绍研究结果，包括马里兰州公立学校系统的学生;并与马里兰州大学的路易斯·斯托克斯少数民族参与联盟项目合作，指导一名本科生研究人员。海洋生物碳泵是减少大气二氧化碳浓度的一个关键过程，是在初级生产和随后从海洋表面运输到深渊的过程中将二氧化碳固定到有机材料（Corg）中。在大陆架上，出口的总Corg的比例远远大于公海，因此即使是大陆架上生物生产力的微小波动也会对全球碳预算产生重大影响。在大部分海洋表层，生物生产力受到营养物质可获得性的限制，营养物质的垂直迁移受到湍流混合的控制。在与陆架/斜坡地形相互作用期间，一部分潮汐能量在转换成内波期间损失于湍流，内波在向岸上移动时损失于湍流。这一机制可能会增加大陆架上的垂直养分通量和生物生产力。鉴于潮汐在世界范围内的普遍性和频率（数小时至数月），内部潮汐-陆架断裂相互作用引起的混合可能是全球重要的表层海洋生态系统营养供应机制。本研究的目的是量化内波对垂直营养盐通量的影响。该研究员将使用一个推进式自动水下航行器，在新英格兰大陆架南部的春潮和小潮期间，对两个半日潮汐周期内的垂直湍流混合率和硝酸盐浓度分布进行同时现场测量。这些测量结果将用于在前所未有的时间和空间尺度上估计垂直硝酸盐通量的变化。该研究员测试的假设，即潮汐能耗散与大陆架边缘的相互作用所造成的增加垂直湍流混合的速度，从而垂直养分通量，在中大西洋湾的透光层的底部附近。

The marine biological carbon pump transforms carbon dioxide into organic carbon and transports it from the surface ocean to the abyss. Biological productivity in the oceans is dependent on the rate at which deep water nutrients mix upward into the surface ocean. Tides are believed to contribute to this mixing in the coastal ocean, but we do not know the extent to which they influence the biological carbon pump. In this project, the fellow will address the fundamental question: Do tides significantly impact biological production and organic carbon export in the coastal ocean by increasing the rate at which essential nutrients enter the sunlit surface ocean? In addition, the fellow will broaden participation of underrepresented groups in the ocean sciences by leading hands-on educational activities teaching introductory robotics to students of Baltimore City public schools; presenting findings to the local community during the an open house at Horn Point Laboratories, including students in the Maryland public school system; and collaborating with the University of Maryland's Louis Stokes Alliance for Minorities Participation program to mentor an undergraduate researcher. The marine biological carbon pump, a critical process in reducing atmospheric carbon dioxide concentration, is the fixation of carbon dioxide into organic material (Corg) during primary production and subsequent transport from the surface ocean into the abyss. Over the continental shelves, the proportion of total Corg that is exported is much greater than that in the open ocean, so even small fluctuations in biological productivity over the shelves can have a large impact on the global carbon budget. In much of the surface ocean, biological productivity is limited by nutrient availability and the vertical transport of nutrients is controlled by turbulent mixing. During interaction with the shelf/slope topography, a portion of tidal energy is lost to turbulence during conversion into internal waves, which lose further energy to turbulence as they move onshore. This mechanism likely increases the rate vertical nutrient flux and biological productivity over the continental shelves. Given the ubiquity and frequency (hours to months) of tides worldwide, mixing caused by internal tide-shelf break interaction may be a globally important mechanism of nutrient supply to surface ocean ecosystems. The goal of this study is to quantify the effect of internal waves on vertical nutrient flux. Using a propelled Autonomous Underwater Vehicle (AUV), the fellow will make simultaneous in-situ measurements of vertical turbulent mixing rate and nitrate concentration profiles over two semidiurnal tidal cycles during both a spring and neap tide over the southern New England shelf. These measurements will be used to estimate the change in vertical nitrate flux on unprecedented temporal and spatial scales. The fellow test the hypothesis that tidal energy dissipation caused by the interaction with the continental shelf edge will increase the rate of vertical turbulent mixing, and thus vertical nutrient flux, near the base of the euphotic zone in the Mid-Atlantic Bight.