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Northerly surface wind events over the eastern North Pacific Ocean: Spatial distribution, seasonality, atmospheric circulation, and forcing.

机译：北太平洋东部北部的地面风向事件：空间分布，季节性，大气环流和强迫。

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摘要

The climate of the coastal US West coast is characterized by cool, alongshore, northerly wind from the Oregon border to the Southern California Bight, south of Point Conception. New datasets, including surface wind estimates derived from satellite scatterometer and North American Regional Reanalysis fields allow for a more detailed exploration than has heretofore been possible. This thesis examines episodes of enhanced northerly surface wind to determine the spatial and temporal character of the surface wind along and offshore of the California coast and the 3-D structure and seasonality of the atmosphere associated with the wind episodes. A deterministic approach is employed to enhance understanding of fundamental processes rather than improve predictability. The methodology includes diagnostic spatial and temporal analysis and numerical sensitivity experiments. Processes known to affect coastal wind are investigated to gain a better understanding of the role of possible mechanisms driving northerly wind events. It is found that the spatial and temporal structure of wind offshore of California is characterized by episodes of enhance equatorward surface wind that often extend from Cape Mendocino to Hawaii. Wind events typically last four days and are present 20% of the time during January-August. The summer circulation structure associated with wind events is fundamentally different than winter and spring. For instance the surface and upper-air circulation patterns associated with wind events are co-located in winter and 90° out-of-phase in summer. Wind events are nearly always accompanied by a strong trough in the upper-air circulation that is directly above or just east of the coast. The analysis concludes that troughs are a nearly universal forcing mechanism for wind events, while the low-level atmospheric thermal gradient across the coast also plays an important, but less consistent role in wind events. A hypothesis is developed suggesting that southeastward movement of the North Pacific High may be a sufficient forcing mechanism for wind events in summer, but a trough along the coast is a necessary ingredient in winter. Other forcing mechanisms, feedbacks, and processes may also be important in reinforcing the circulation associated with wind events.
机译：从俄勒冈州边界到Point Conception以南的南加州湾，美国西海岸沿海地区的气候为凉爽，近岸，北风。新的数据集，包括从卫星散射仪和北美区域再分析场获得的地表风估计值，可以进行比以往更详细的探索。本论文研究了增强的北表面风事件，以确定沿着加利福尼亚海岸和离岸的表面风的时空特征，以及与风事件相关的3D结构和大气季节。确定性方法用于增强对基本过程的理解，而不是提高可预测性。该方法包括诊断性时空分析和数值敏感性实验。对已知会影响沿海风的过程进行了研究，以更好地了解驱动北方风事件的可能机制的作用。发现加利福尼亚海上风的时空结构特征是赤道表面风增强，通常从门多西诺角延伸到夏威夷。风事件通常持续四天，在一月至八月期间占20％的时间。与风事件相关的夏季循环结构与冬季和春季根本不同。例如，与风事件相关的地表和高空环流模式在冬季共同定位，在夏季异相90度。风事件几乎总是伴随着在海岸正上方或正东的高空循环中的一个强低谷。分析得出的结论是，低谷是风事件的一种近乎普遍的强迫机制，而整个海岸的低层大气热梯度在风事件中也起着重要但不太稳定的作用。提出了一个假说，表明北太平洋高压的东南运动可能是夏季风事件的足够强迫机制，但是冬天沿海岸的低谷是必不可少的因素。其他强迫机制，反馈和过程在加强与风事件相关的环流中也可能很重要。

著录项

  • 作者

    Taylor, Stephen V.;

  • 作者单位

    University of California, San Diego.;

  • 授予单位 University of California, San Diego.;
  • 学科 Physical Oceanography.; Physics Atmospheric Science.
  • 学位 Ph.D.
  • 年度 2006
  • 页码 145 p.
  • 总页数 145
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 海洋物理学;大气科学（气象学）;
  • 关键词

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