US GLOBEC: Cross-Frontal Fluxes and Mixing on Georges Bank

美国 GLOBEC：乔治滩上的跨锋通量和混合

• 批准号: 9806650
• 负责人: David Hebert
• 金额: $ 47.62万
• 依托单位: University of Rhode Island
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-11-15 至 2002-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9806650&HistoricalAwards=false
• 关键词: US; GLOBEC; Cross; Frontal; Fluxes

Cross-Frontal Fluxes and Mixing on Georges BankD. Hebert and J. BarthOne of the overall goals of the NW Atlantic/Georges Bank GLOBEC Study is "to determine the processes that control the Georges Bank circulation and transport of biological, chemical, and geological materials in a strongly tidal- and buoyancy-driven system and to determine the physical and biological processes that control the population dynamics of the target species For Phase III of this program, the primary focus of research will be on cross-frontal exchange processes. For this project, the investigators will determine the three-dimensional circulation associated with the Northeast Peak Front (in late March/early April), the Shelf/Slope Front, and the Tidal Mixing Front on the southern flank of Georges Bank (in mid-June). The dynamics of these different fronts over a fortnightly period will be studied. The effect of the variability in the tidal currents (both at the semi-diurnal and fortnightly time-scales) on the cross-frontal exchange processes will be examined. An attempt will be made to determine the dynamics of the cross-frontal exchange and the rate of cross-frontal exchange for each front. To address these goals, high-resolution SeaSoar surveys will be made around an isopycnal Lagrangian float placed initially in the center of the front. The SeaSoar will have dual temperature and conductivity sensors on the CTD, a WET LABS ac-9 optical package (absorption and attenuation data collected at 9 frequencies), a fluorometer and MicroSoar. MicroSoar has fast temperature and conductivity sensors allowing estimates of the temperature variance dissipation rate (i.e., temperature microstructure) to be made. A shipboard Acoustic Doppler Current Profiler (ADCP) will provide horizontal velocity data. The trajectory of the isopycnal float will provide the cross-frontal exchange pathway for one location for each deployment. Analysis of the CTD and ADCP data will be used to determine the dynamics of this exchange pathway. The salinity, temperature and ac-9 data will be used to characterize the water masses present. Combinations of the nine absorption and attenuation channels can be used as surrogate "tracers" to track cross-frontal exchange pathways. Repeated surveys may allow the exchange rates to be determined. The microstructure data will provide information if turbulent mixing processes are important and, if so, where they occur. The results of this work will provide insight on how water (and other properties of the water) are exchanged across the different types of fronts found on Georges Bank. With the measurements of biological processes and distributions at the same location made by other GLOBEC PIs, the effect of physical forcing on these biological processes can be addressed.

乔治河岸D的交叉锋通量和混合。西北大西洋/乔治银行GLOBEC研究的总体目标之一是“确定控制乔治银行循环和生物，化学和地质材料在强烈潮汐和浮力驱动系统中运输的过程，并确定控制目标物种种群动态的物理和生物过程。研究的主要重点将是跨锋交换过程。 对于这个项目，调查人员将确定与东北峰锋（3月下旬/4月上旬），陆架/斜坡锋和乔治银行南侧的潮汐混合锋（6月中旬）相关的三维环流。 将每两周研究一次这些不同锋面的动态。 将检查潮流（在半日和每两周的时间尺度上）的变化对跨锋面交换过程的影响。 尝试将作出决定的动态的跨锋面交换和跨锋面交换率为每个前线。 为了实现这些目标，高分辨率的SeaSoar调查将围绕最初放置在前线中心的等密度拉格朗日浮标进行。 SeaSoar将在CTD上安装双温度和电导率传感器，一个WET LABS ac-9光学包（在9个频率下收集吸收和衰减数据），一个荧光计和MicroSoar。 MicroSoar具有快速的温度和电导率传感器，可以估计温度变化耗散率（即，温度微结构）。 船上的声学多普勒海流剖面仪（ADCP）将提供水平流速数据。 等密度浮标的轨迹将为每次部署的一个位置提供跨锋面交换路径。 CTD和ADCP数据的分析将用于确定这种交换途径的动态。 盐度、温度和ac-9数据将用于描述存在的水团的特征。 九个吸收和衰减通道的组合可以用作替代“示踪剂”来跟踪跨锋面交换路径。 通过反复调查可以确定汇率。 微观结构数据将提供信息，如果湍流混合过程是重要的，如果是这样，他们发生。 这项工作的结果将提供关于水（和水的其他属性）如何在乔治银行发现的不同类型的前线之间交换的见解。 通过其他GLOBEC PI在同一地点对生物过程和分布的测量，可以解决物理强迫对这些生物过程的影响。