CAREER: Physical Modulation of Dissolved Oxygen in Chesapeake Bay

物理过程在控制切萨皮克湾夏季缺氧的年际变化中起主导作用。海湾缺氧发展的经典模型假设了一个简单的一维平衡，其中生物需氧量超过了湍流混合通过斜斜的垂直溶解氧供应。PI最近的工作提出了一个新的缺氧调节模型，其中溶解氧不是通过直接的垂直混合，而是通过横向环流和边界附近混合的相互作用提供给次斜斜水域。假设风力驱动的横向环流是向易缺氧地区提供溶解氧的主要机制，并且该机制的有效性对风向和河口水深测量都很敏感。数值模拟和历史数据都支持这一假设，但需要全面的现场测量来充分验证这一假设。该项目的总体研究目标是全面了解包括风、潮汐和密度分层在内的物理强迫如何调节切萨皮克湾的溶解氧。这一目标将通过对环流、密度分层和河口测深之间的相互作用以及这些相互作用最终如何控制湍流标量（盐度、温度和氧气）通量发生的时间和地点的全面检查来实现。切萨皮克湾的公众意识和当地对缺氧的重要性使其成为一个理想的社会科学问题，为大汉普顿路地区的学生和公众提供全面的基于情境的教育计划。该项目的教育活动将促进对切萨皮克湾缺氧的跨学科检查，强调生物和物理过程之间的相互作用，并强调科学在制定公共政策方面的作用。知识价值：了解环流如何与密度分层相互作用以控制湍流标量通量发生的时间和地点是沿海和河口海洋学中的一个基本问题。它显著影响着广泛的物理和生物地球化学过程，并对缺氧具有一级控制作用。缺氧是沿海和河口水域面临的最紧迫的水质问题之一，但很少有详细的研究解决了调节溶解氧的湍流混合过程。这里收集的测量数据将代表对切萨皮克湾湍流混合的最全面的研究，包括对氧气直接湍流通量的前所未有的测量。更广泛的影响：本研究的科学目标对于评估恢复切萨皮克湾水质的努力具有根本的重要性。这项研究的结果将有助于监管机构和政策制定者更好地设计和评估这个经济和生态重要的河口的修复工作。本提案的教育活动旨在通过针对不同教育水平的普通公众和学生，提高关于缺氧问题的科学素养。夏季缺氧/缺氧研究项目（SHARP）的发展将通过与汉普顿大学的合作，为本科生提供独特的研究机会，特别是针对代表性不足的少数民族。将缺氧纳入切萨皮克互动建模计划（CHIMP）将为教育公众关于切萨皮克湾最重要的水质问题之一提供一个强大的工具。这个新工具将提供给已经使用原始版本CHIMP的广大教育工作者，并将通过弗吉尼亚水族馆的展示，用于教育参与指导青年科学家计划的中学生和普通公众。

Physical processes play a dominant role in controlling the inter-annual variability of summertime hypoxia in Chesapeake Bay. The classical model for the development of hypoxia in the Bay assumes a simple one-dimensional balance in which biological oxygen demand exceeds the vertical supply of dissolved oxygen through the pycnocline by turbulent mixing. The PI's recent work suggests a new model for the modulation of hypoxia in which dissolved oxygen is supplied to the sub-pycnocline waters not through direct vertical mixing, but rather through the interactions of lateral circulation and mixing near the boundaries. It is hypothesized that wind-driven lateral circulation is the dominant mechanism that supplies dissolved oxygen to regions susceptible to hypoxia, and that the effectiveness of this mechanism is sensitive to both wind direction as well as estuarine bathymetry. This is supported by both numerical simulations and historical data, but comprehensive field measurements are required to adequately test this hypothesis. The overall research objective of this project is to develop a comprehensive understanding of how physical forcing, including winds, tides and density stratification, modulates dissolved oxygen in Chesapeake Bay. This objective will be achieved through a comprehensive examination of the interactions between circulation, density stratification and estuarine bathymetry and how these interactions ultimately govern when and where the turbulent scalar (salinity, temperature, and oxygen) flux occurs. The public awareness and local importance of hypoxia in Chesapeake Bay make it an ideal socio-scientific issue for a comprehensive context-based education plan for students and the general public in the greater Hampton Roads area. The educational activities in this project will promote an interdisciplinary examination of hypoxia in Chesapeake Bay that highlights the interactions between biological and physical processes and stresses the role of science in shaping public policy.Intellectual Merit: Understanding how circulation interacts with density stratification to control when and where turbulent scalar flux occurs is a fundamental problem in coastal and estuarine oceanography. It significantly impacts a wide range of physical and biogeochemical processes and exerts a first order control on hypoxia. Hypoxia is one of the most pressing water quality issues facing coastal and estuarine waters, yet there are few if any detailed studies that resolve the turbulent mixing processes that modulate dissolved oxygen. The measurements collected here will represent the most comprehensive examination of turbulent mixing in Chesapeake Bay, including unprecedented measurements of the direct turbulent flux of oxygen.Broader Impacts: The scientific goals of this study are of fundamental importance to assessing efforts to restore water quality in Chesapeake Bay. The results from this research will help regulatory agencies and policymakers better design and assess restoration efforts in this economically and ecologically important estuary. The educational activities of this proposal are designed to promote scientific literacy about the issue of hypoxia by targeting both the general public and students across a wide range of educational levels. The development of the Summer Hypoxia/Anoxia Research Program (SHARP) will provide unique research opportunities for undergraduate students, specifically targeting underrepresented minorities through a partnership with Hampton University. The integration of hypoxia into the Chesapeake Interactive Modeling Program (CHIMP) will provide a powerful tool for educating the public about one of the most important water quality issues in Chesapeake Bay. This new tool will be made available to the extensive group of educators already using the original version of CHIMP, and it will be used to educate middle school students involved in the Mentoring Young Scientist Program and the general public through a display at the Virginia Aquarium.