Orographic Forcing of the Coastal Atmospheric Boundary Layer

沿海大气边界层的地形强迫

• 批准号: 9526138
• 负责人: David Rogers
• 金额: $ 46.26万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-03-15 至 2000-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9526138&HistoricalAwards=false
• 关键词: Orographic; Forcing; Coastal; Atmospheric; Boundary

9526138 Rogers Coastal mountains form a barrier to the wind field that may affect both the downstream and upstream evolution of the local air flow. Local regions of high or low pressure generated by the coastal zone can become trapped and propagate along the coastline. Energetic, disturbances that exist for between two and six days are of particular interest. These features can cause significant changes in the local weather in the coastal zone, for example, replacing clear skies with clouds and fog, and causing intensification and reversals of the wind field. These systems are well documented, but no studies have characterized their dynamical structure, origin, interaction with the mean boundary layer and the development of the cloud-capped layer that accompanies these events. Accelerations of the flow associated with coastal barriers give rise to strong wind forcing of the coastal ocean and rapid variations in the speed of the low level air flow. These orographically-forced flows have a significant effect on the exchange of heat, moisture, momentum and trace constituents between the ocean and the atmosphere. Since these flows are constrained by the topography, they are often stationary and persistent, consistently affecting a particular area of the coastline. While the basic structure of these features is known, they have been documented on only a few occasions and no systematic study has been directed specifically to identifying the dynamics of these features and their interactions with the thermal circulation that is also a significant mesoscale feature of the summer-time California coastal zone. This work will focus on in situ measurements of the along shore and across shore structure of the boundary layer using aircraft and surface based measurements. Aircraft instruments will provide direct measurements of the mean and turbulent structure of the coastal atmosphere with coincident lidar measurements of the deformation of the marine bounda ry layer inversion and in situ cloud microphysical measurements of coastal clouds and aerosols. An important result will be the ability to resolve the temporal and spatial scales that dominate the variability of the mesoscale wind field along parts of the California coast, which may have a significant impact of mesoscale forecasting and numerical modeling in complex terrain. ***

小行星9526138 海岸山脉形成了风场的屏障，可能会影响当地气流的下游和上游演变。 由海岸带产生的局部高压或低压区域可能被困并沿沿着传播。 持续两到六天的高能扰动特别令人感兴趣。这些特徴可导致沿海地区的当地天气发生重大变化，例如，云和雾取代晴朗的天空，并导致风场加剧和逆转。这些系统都有很好的文献记载，但没有研究表明它们的动力结构、起源、与平均边界层的相互作用以及伴随这些事件的云顶层的发展。 与海岸屏障相关的气流加速引起沿海海洋的强风强迫和低空气流速度的快速变化。 这些地形强迫的流动对海洋和大气之间的热量、水分、动量和微量成分的交换有显著的影响。由于这些水流受到地形的限制，它们往往是静止和持续的，不断影响海岸线的特定区域。 虽然这些功能的基本结构是已知的，他们已经被记录在少数场合，并没有系统的研究一直专门针对确定这些功能的动态及其相互作用的热循环，这也是一个显着的夏季加州沿海地区的中尺度功能。 这项工作将集中在现场测量的沿着海岸和跨海岸结构的边界层使用飞机和地面为基础的测量。 飞机仪器将提供沿海大气的平均和湍流结构的直接测量，同时激光雷达测量海洋边界层反演的变形和沿海云和气溶胶的现场云微物理测量。 一个重要的结果将是能够解决的时间和空间尺度，占主导地位的变化的中尺度风场沿着部分加州海岸，这可能有显着的影响中尺度预报和数值模拟在复杂的地形。 ***