Understanding and Modelling Natural and Forced Variability of Near-Surface Winds

近地表风控制着大气和下垫面之间的质量、能量和动量的交换；它们影响着地表温度和空气质量，是一种日益重要的能源资源；它们的极端情况对自然和建筑环境构成了危害。拟议的研究包括四个免费的与风有关的研究项目，解决该领域的紧急问题。*未来的气候变化将与风能和太阳能的变化(以及它们的互变性，可以缓解可再生能源的间歇性)有关。在第一个项目中，我们将使用气候模型模拟的集合来量化与21世纪北美可再生能源相关的不确定性。我们还将把动力资源的年际和年代际变化与厄尔尼诺等气候变化的主要模式联系起来。近地表风速是由行星边界层(PBL)上的过程决定的。夜间边界层表现为两种不同的温度和风廓线。这些结构在天气和气候模型中的表现很差，导致了温度和风的偏差。第二个项目将把新的数学工具应用到理想化的物理模型中，以研究这些制度。然后，我们将考虑不规则天气变化在驾驶制度转变中的作用。海面风分量的极端值在很大程度上受到其平均值附近波动的不对称性的影响。我开发了一套理想化的模型来解释这种行为。双谱为这些不对称性的物理起源提供了一种新的视角，它将这种不对称性划分为不同的频率贡献。在第三个项目中，我们将使用双谱进一步研究观测和理想化模式中风分量波动不对称的物理。*天气和气候模式中的海气交换取决于风速。这些模式中没有解决的小尺度风对通量增强有贡献，模式必须将其参数化。虽然参数化通常将唯一的亚格子尺度通量分配给所解析流动的每个唯一状态，但我们已经证明，事实上，这些修正更好地由概率分布来表示。第四个项目将把我们先前的分析扩展到更长的记录和更大的领域，目标是在一个可操作的天气模式中实现这样的参数化。**

Near-surface winds control the exchange of mass, energy, and momentum between the atmosphere and the underlying surface; they influence surface temperature and air quality and represent an energy resource of growing importance; and their extremes represent hazards to the natural and built environments. The proposed research is comprised of four complimentary wind-related research projects addressing urgent questions in the field.******Future climate changes will be associated with changes in wind and solar energy (as well as of their co-variability which can mitigate the intermittency of renewables). In the first project, we will use ensembles of climate model simulations to quantify uncertainties related to North American renewable energy in the 21st century. We will also relate interannual and interdecadal variability in power resources to dominant modes of climate variability such as El Nino.******Near-surface wind speed is determined by processes across the Planetary Boundary Layer (PBL). The nocturnal PBL displays two regimes, with very different temperature and wind profiles. These structures are poorly represented in weather and climate models, resulting in temperature and wind biases. The second project will apply novel mathematical tools to idealized physical models to investigate these regimes. We will then consider the role of irregular weather variations in driving regime transitions.******Extremes of sea surface wind components are substantially affected by asymmetries in their fluctuations around the mean. I have developed a set of idealized models to account for this behaviour. A novel perspective on the physical origin of these asymmetries is provided by the bispectrum, which partitions this asymmetry into different frequency contributions. In the third project, we will use bispectra to further investigate the physics of wind component fluctuation asymmetry in observations and in an idealized model. ******Air-sea exchanges in weather and climate models depend on wind speed. Small-scale winds not resolved in these models contribute to flux enhancements that the models must parameterize. While parameterizations normally assign a unique subgrid-scale flux to each unique state of the resolved flow, we have shown that in fact these corrections are better represented by probability distributions. The fourth project will extend our earlier analysis to longer records and larger domains, with the goal of implementing such a parameterization in an operational weather model. **