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

乔治河岸的交叉锋面通量和混合。Hebert和J. barthonnw Atlantic/Georges Bank GLOBEC研究的总体目标之一是“确定在强潮汐和浮力驱动的系统中控制Georges Bank生物、化学和地质物质循环和运输的过程，并确定控制目标物种种群动态的物理和生物过程。对于该计划的第三阶段，研究的主要重点将是交叉交换过程。”在这个项目中，研究人员将确定与东北峰锋（3月下旬/ 4月初）、陆架/斜坡锋和乔治海岸南侧潮汐混合锋（6月中旬）相关的三维环流。这些不同锋面在两周内的动态将被研究。将研究潮汐流（在半日和两周时间尺度上）的变异性对横额交换过程的影响。将尝试确定正面交换的动态和每个锋面的正面交换率。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方中心的等距拉格朗日浮子进行。SeaSoar将在CTD上安装双温度和电导率传感器、WET实验室ac-9光学封装（在9个频率上收集吸收和衰减数据）、荧光计和MicroSoar。MicroSoar具有快速的温度和电导率传感器，可以估计温度方差耗散率（即温度微观结构）。舰载声学多普勒电流剖面仪（ADCP）将提供水平速度数据。等距浮动的轨迹将为每次部署提供一个位置的横额交换路径。对CTD和ADCP数据的分析将用于确定这一交换途径的动力学。盐度、温度和ac-9数据将用于表征存在的水团。九种吸收和衰减通道的组合可以用作替代的“示踪剂”来跟踪交叉额叶交换通路。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，在哪里发生。这项工作的结果将提供关于水（和水的其他性质）如何在乔治海岸不同类型的锋面之间交换的见解。通过其他GLOBEC pi对同一地点的生物过程和分布进行测量，可以解决物理强迫对这些生物过程的影响。

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.