Variability and Predictability of Near-Surface Winds

地球表面附近空气运动最为人所熟知的特征是它的可变性。虽然每日或季节时间尺度的变化是有规律的，但大多数近地表风速的变化是不规则的--从短时间尺度的湍流波动到由大规模天气和气候过程驱动的较长时间尺度的变化。了解近地表风的可变性很重要，因为它们是大气与陆地或海洋表面之间质量、能量和动量交换的主要控制因素；风能是一种重要的可再生能源；极端风可能对自然和已建环境造成破坏。 尽管基本的物理原理是相同的，但风在陆地上的表现与在水面上的不同。同样，不同的物理过程决定了它在不同的时间尺度上的可变性。我研究的一个中心目标是对这些对可变性的控制以及由此对可预测性的影响建立一个基本的理解。为此目的提出了以下项目。我和我的研究小组将： 1.利用应用数学和统计学中的现代技术，研究近地表风场之间的转换，我们已经证明，这种“风场”与异常强烈的夜间风有关。 2.确定海洋表面温度的变化如何调节海洋上空近表面风的平均值、变化性和极端情况。 3.研究使风观测与我们的风模型相适应的问题的新方法，以提高其量化效用。 4.审查观测到的来自不同方向的风在统计可预测性方面存在差异的物理原因。 5.量化风速在不同时间尺度上的可预测性变化。 6.评估对来自不同方向的风的风可变性的“记忆”以不同的速度减少这一事实的物理控制。 这项拟议的研究在我们近年来开展的基础研究的基础上建立了新的和重要的方向。这项新的研究将在我们对地面风的变异性和极端的基本物理和数学理解方面取得重要进展，并对在综合气候模式中对其进行模拟以及对风能资源的评估和预测产生影响。

The most familiar feature of the motion of air near the Earth's surface is its variability. While variations on daily or seasonal timescales are regular, most near-surface wind variability is irregular - from short-timescale turbulent fluctuations to longer timescale variations driven by large-scale weather and climate processes. Understanding the variability of near-surface winds is important because they are a leading-order control on exchanges of mass, energy and momentum between the atmosphere and the land or ocean surfaces; wind energy is a significant renewable energy source; and wind extremes can be damaging to the natural and built environments. Although the underlying physics is the same, wind behaves differently over land than over water. As well, different physical processes determine its variability on different timescales. A central goal of my research is to build a fundamental understanding of these controls on variability and the consequent implications for predictability. The following projects are proposed towards this end. My research group and I will: 1. use modern techniques from applied mathematics and statistics to investigate transitions between near-surface wind "regimes" which we have shown are associated with unusually strong nighttime winds. 2. determine how changes in sea surface temperature modulate the mean, variability, and extremes of near-surface wind over the ocean. 3. study new approaches to the problem of fitting wind observations to our wind models, to improve their quantitative utility. 4. examine the physical reasons for the observed difference in the statistical predictability of winds coming from different directions. 5. quantify how the predictability of wind speed changes on different timescales. 6. assess the physical controls on the fact that the "memory" of wind variability falls off at different rates for winds from different directions. This proposed research builds in new and important directions on the foundational research we have carried out in recent years. The new research will result in important advances in our fundamental physical and mathematical understanding of the variability and extremes of surface winds, with implications for their simulation in comprehensive climate models and for the assessment and prediction of the wind energy resource.