Collaborative Research: LIDAR Studies of Lateral Dispersion in the Seasonal Pycnocline

合作研究：季节性密萝斜层横向色散的激光雷达研究

• 批准号: 0751734
• 负责人: Miles Sundermeyer
• 金额: $ 38.17万
• 依托单位: University of Massachusetts, Dartmouth
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-11-01 至 2013-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0751734&HistoricalAwards=false
• 关键词: Collaborative; Research; LIDAR; Studies; Lateral

Intellectual Merit. Lateral stirring and mixing in the stratified ocean at scales of 30 m to 3 km are poorly understood. Yet mixing at these scales is an important aspect of marine ecology. Also, mixing at these scales must usually be parameterized in numerical models of ocean circulation and ocean biogeochemistry, since such small scales are not explicitly resolved in most models. The aim of the proposed work is to visualize and to understand the processes governing lateral stirring and mixing at these small scales. One hypothesis to test is that lateral stirring is driven by the relaxation of patches of weakly stratified water created by vertical mixing events. Another is that it is due to the combined action of vertical mixing and vertical shear in the horizontal velocities. There may also be stirring processes independent of vertical mixing. Drs. Ledwell and Sundermeyer will test these hypotheses and ideas and be prepared to formulate others on the basis of their experiments. The approach is to release patches of fluorescent dye in the stratified upper ocean off Bermuda, where the water is very clear. Rapid surveys of the evolving dye patches will be made with a scanning LIDAR (LIght Detecting and Ranging) system carried by a low-flying aircraft. Profiles made by a small boat in the patches will provide calibration data for the airborne measurements and would sample hydrographic structures of interests within the patches. The small boat will be tended by a research vessel, from which measurements will be made of inherent optical properties of the water, water velocity profiles, ambient radiation and meteorological conditions near the patches. The airborne LIDAR system will be a modification of a topographic mapping system operated by the NAVAIR Flight Facility. It will have a depth resolution of 1 m and a lateral resolution of 2 to 3 meters, and will sense dye to depths of 30 meters. Navigation and mapping of the dye patches will be relative to a set of drifting buoys with drogues set at the depth of the releases, and with GPS receivers and radio transmitters for communication with the ship, the small boat, and the aircraft. The experiments will be conducted during the month of July when the water is usually the clearest and when the wind-mixed layer is the thinnest. The releases will be between 10 and 20 meters below the surface, and each experiment will last on the order of 24 hours. The dye distribution will be inferred from sophisticated inversions of the returned signal in both the transmitted and fluoresced frequency bands. Broader Impacts. Understanding of the physical processes at work in small scale lateral mixing in the ocean will be of direct benefit to those trying to study ocean ecosystems and hence to those working to protect the health of the ocean, as well as those trying to develop numerical models of the ocean for this and a great variety of other practical purposes. We will entrain undergraduate and/or graduate students and a school teacher, through the ARMADA program, into the field work, which will be conducted during the summer break. A post doctoral fellow will be entrained for the field work and analysis. Development of the NASA LIDAR system at Wallops Flight Facility into one that can effectively see into the upper ocean, whether dye is used or not, will be a substantial addition to the research tools available to oceanographers.

智力优点。人们对 30 m 至 3 km 尺度的分层海洋中的横向搅拌和混合知之甚少。然而，这些规模的混合是海洋生态学的一个重要方面。此外，这些尺度的混合通常必须在海洋环流和海洋生物地球化学的数值模型中参数化，因为在大多数模型中没有明确解决如此小的尺度。拟议工作的目的是可视化并理解控制这些小规模横向搅拌和混合的过程。需要测试的一个假设是，横向搅拌是由垂直混合事件产生的弱分层水斑的松弛驱动的。另一种是由于水平速度中垂直混合和垂直剪切的共同作用。还可以存在独立于垂直混合的搅拌过程。博士。莱德韦尔和桑德迈尔将测试这些假设和想法，并准备在他们的实验的基础上制定其他假设和想法。该方法是在百慕大附近的分层上层海洋中释放荧光染料，那里的海水非常清澈。将使用低空飞行的飞机携带的扫描激光雷达（光探测和测距）系统对不断变化的染料斑块进行快速调查。由小船在斑块中绘制的剖面将为机载测量提供校准数据，并对斑块内感兴趣的水文结构进行采样。这艘小船将由一艘研究船管理，对水的固有光学特性、水速剖面、环境辐射和斑块附近的气象条件进行测量。机载激光雷达系统将是由海军航空飞行设施运营的地形测绘系统的改进版。它将具有 1 m 的深度分辨率和 2 至 3 米的横向分辨率，并能感应 30 米深度的染料。染料斑块的导航和测绘将与一组漂流浮标相关，这些浮标带有设置在释放深度的锥套，以及用于与船舶、小船和飞机通信的 GPS 接收器和无线电发射器。实验将在七月份进行，此时水通常最清澈，风混合层最薄。释放将在地表以下 10 至 20 米处进行，每次实验将持续大约 24 小时。染料分布将通过透射频带和荧光频带中返回信号的复杂反转来推断。更广泛的影响。了解海洋小规模横向混合的物理过程将直接有益于那些试图研究海洋生态系统的人，从而有益于那些致力于保护海洋健康的人，以及那些试图开发海洋生态系统数值模型的人。海洋用于此目的以及其他各种实际目的。我们将通过 ARMADA 计划邀请本科生和/或研究生以及一名学校教师参与将在暑假期间进行的实地工作。将聘请一名博士后研究员进行实地工作和分析。将瓦洛普斯飞行设施的 NASA 激光雷达系统开发成一个无论是否使用染料都可以有效观察上层海洋的系统，将是海洋学家可用的研究工具的重要补充。