Collaborative Research: GLOBEC: Mapping the Evolution of Meoscale Jets and Eddies in the Upwelling Ecosystem off Cape Blanco, Oregon, Using Long-Range High Frequency Radar

PIs将在海洋观测系统中开发一种新的能力，能够对整个沿海上升流系统（包括相关的射流和涡流）的表面流进行时空测绘。这种能力包括使用沿海岸线部署的高频（BY）雷达仪器。这些测量的新方面是，它将使用调到B17频段的低频端（约5 MHz）的系统，而不是现在常用的在12 MHz和25 MHz之间工作的系统。射程能力的差异是巨大的。标准系统通常测量距离海岸30英里至50公里的距离，距离分辨率约为2公里。这里提供的新数据表明，这些相同的仪器在5兆赫频率下工作，能够测量距离海岸200公里的距离，距离分辨率约为6伊恩。这个范围已经被证明是通过结合商用CODAR/SeaSonde中包含的非常高效的发射机技术和为密歇根大学生产的调谐发射天线！多频海岸雷达（MCR）。我们建议使用这些雷达的三个站点阵列，以俄勒冈州布兰科角为中心，在大约350公里x 180公里的范围内获得三年时间序列的中尺度地表流每日地图。在GLOBEC东北太平洋（NEP）项目期间，该地区是计划在一系列空间和时间尺度上进行密集的原位生物物理采样的重点。最近的研究表明，在上升流季节，布兰科角通常是物理状态的一个分离点，在那里，被困在海岸边的陆架射流向北与海岸分离，向外流动，在更南边留下一个富含涡流的状态（Smith, 1995； Barth和Smith， 1998）。GLOBEC NEP的一个核心假设是，中尺度环流的时空变化主导着沿海地区浮游动物生产、分布、滞留和损失的物理强迫。雷达导出的地图将用于研究涡旋和喷流的特性，以及粒子在表层的路径。pi将检查涡旋产生的实例，以确定它们的形成频率，它们是否优先发生在特定地点，以响应特定的风强迫事件，在冬季和夏季。传播特性和时空变化的强度和规模将被检查。涡旋-喷射和涡旋-涡旋相互作用预计将被雷达很好地捕捉到，它可以通过多云的天空进行观测。将通过季节确定喷流核心位置和速度的统计数据，并研究分离事件与风力之间的关系。中尺度洋流的时间序列图将为建模者提供测试用例。它们还将补充卫星遥感的地表温度、海洋颜色和地表高度。

GLOBEC Mapping the Evolution of Mesoscale Jets and Eddies in the UpwellingEcosystem off Cape Blanco, Oregon, using Long-Range High-Frequency RadarThe PIs will exploit a new capability in ocean observing systems that will enable the space and time mapping of surface currents over an entire coastal upwelling system, including associated jets and eddies. The capability involves the use of High Frequency (BY) radar instruments deployed along the shoreline. The new aspect of these measurements is that it will use systems tuned to the low-frequency end of the B17 band, around 5 MHz, rather than the now commonly used systems that operate between 12 MHz and 25 MHz. The difference in range capability is dramatic. The standard systems typically measure 30 Ian to 50 km from shore with range resolution on the order of 2 km. New data presented here shows that these same instruments operating at 5 MHz are capable of measuring 200 km from shore with range resolution on the order of 6 Ian. This range has been proven by combining the very efficient transmitter technology contained in the commercially available CODAR/SeaSonde with a tuned transmit antenna produced for the University of Michigan!s Multifrequency Coastal Radar (MCR).We propose to use a three-site array of these radars to obtain a three-year time-series of daily maps of mesoscale surface currents over an area approximately 350 km x 180 km in extent, centered on Cape Blanco, Oregon. This region is the planned focus of intense in-situ biophysical sampling over a range of space and time scales during the GLOBEC Northeast Pacific (NEP) program. Recent studies show that Cape Blanco is often a separation point in physical regimes during the upwelling season, where a shelf-trapped alongshore current jet to the north separates from the coast and flows offshore, leaving an eddy-rich regime further south (Smith, 1995; Barth and Smith, 1998). A core hypothesis of GLOBEC NEP is that spatial and temporal variability in mesoscale circulation dominates the physical forcing on zooplankton production, distribution, retention and loss in coastal regions. The radar-derived maps will be used to study the properties of the eddies and jets, and the pathways of particles in the surface layer. The PIs will examine the instances of eddy generation, to determine their frequency of formation, whether they occur preferentially at particular locations, in response to particular wind-forcing events, in winter as well as summer. The propagation characteristics and time-space variations in intensity and scale will be examined. Eddy-jet and eddy-eddy interactions are expected to be well captured by the radar, which can make observations through periods of cloudy skies. Statistics of jet core location and speed will be determined through the seasons, and the relationship between separation events and wind forcing will be examined. Time-series maps of mesoscale currents will provide test cases for modelers. They will also complement satellite remote sensing of surface temperature, ocean color, and surface height.