Collaborative Research: Barrier Jets in the Gulf of Alaska - Causes, Impacts, and Interactions with Other Phenomena

地形突出的海岸线附近的中尺度大气流动对在沿海环境中生活和工作的人产生了巨大的影响。然而，这类局部化的风系统在天气预报中仍然是一个具有挑战性的重要问题。障碍射流是最常见的地形引起的海岸气流之一，它造成了特别危险的天气条件，特别是在阿拉斯加东南部和太平洋西北部。由此产生的大风对生命、财产和经济活动构成威胁。解决这些社会问题需要进行研究，以便更好地了解海岸屏障急流的动态以及形成它们所需的更大范围的天气条件。卫星遥感技术的最新进展为进一步了解障碍物射流提供了机会。例如，合成孔径雷达(SAR)提供了详细的地面风速测量，分辨率为数百米，一侧数百公里的区域。此外，利用合成孔径雷达可以观测到距海岸线1公里以内的风速场。这些合成孔径雷达速度观测可以与其他观测和模型输出相结合，以提供整个沿海地区的高分辨率风矢量图。这些来自过去5年数千个案例的SAR风图存档于约翰·霍普金斯大学应用物理实验室，为发展对阿拉斯加海岸障碍物射流的更好理解提供了独特的资源。这份档案包含了大约100个阿拉斯加湾上空的障碍喷流案例。在这个项目中，首席调查员将利用这一档案以及更多的图像、现场观测和数值模拟，以更好地了解北美西海岸屏障急流的动力学及其形成所需的更大规模的天气条件，从而为这一危险现象的业务预报提供基础。此外，还将调查与屏障急流有关的流动与当地海洋环流之间的相互作用。障碍喷流气候学将被用来绘制与阿拉斯加湾障碍喷流有关的季节性平均风应力异常。这些风应力异常图将被用来确定与障碍物急流相关的平均埃克曼抽水和由此产生的上层海洋响应。这些结果将与系泊浮标的现场观测结果进行核对，并用于检查障碍物喷流对海洋生态系统的影响。这些发现将为渔业以及海洋生物学和物理海洋学研究界提供重要信息。

The mesoscale atmospheric flow near coastlines with prominent terrain has a tremendous impact on those who live and work in the coastal environment. Yet this class of localized wind systems remains a challenging and important problem in weather prediction. One of the most common terrain-induced coastal flows, the barrier jet, creates especially dangerous weather conditions, particularly in southeast Alaska and the Pacific Northwest. The resulting severe winds pose a threat to life, property, and economic activities. Addressing these societal issues requires research to improve understanding of the dynamics of coastal barrier jets and the larger-scale weather conditions required for their formation. Recent advances in satellite remote sensing technology provide an opportunity to further understanding of barrier jets. For example, synthetic aperture radar (SAR) provides detailed measurements of the surface wind speed with resolutions of hundreds of meters over regions several hundred kilometers on a side. Moreover, with SAR the wind speed field can be observed to within 1 km of the coastline. These SAR speed observations can be combined with other observations and model output to provide high-resolution wind vector maps throughout the coastal zone. These SAR-derived wind maps from several thousand cases over the past 5 years, archived at the Johns Hopkins University Applied Physics Laboratory, represent a unique resource for the development of improved understanding of barrier jets along the Alaskan coast. This archive contains on the order of 100 cases of barrier jet flows over the Gulf of Alaska. In this project, the Principal Investigators will exploit this archive, along with additional imagery, in situ observations and numerical simulations to gain a greater understanding of the dynamics of barrier jets along the western coast of North America and of the larger-scale weather conditions required for their formation, thereby providing the basis for operational forecasting of this hazardous phenomenon.Additionally, the interactions between the flow associated with barrier jets and local ocean circulations will be investigated. The barrier jet climatology will be used to map the seasonal mean wind stress anomalies associated with barrier jets in the Gulf of Alaska. These wind stress anomaly maps will be used to determine the mean Ekman pumping associated with barrier jets and the resulting upper ocean response. These results well be checked against in situ observations from moored buoys and used to examine the impact of barrier jets on the marine ecosystem. These findings will provide important information to the fisheries industry as well as the marine biology and physical oceanography research communities.