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

理解近地表风的自然变化和受迫变化并对其进行建模

• 批准号: RGPIN-2019-04986
• 负责人: Monahan, Adam
• 金额: $ 3.72万
• 依托单位: University of Victoria
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=750981
• 关键词: Understanding; Modelling; Natural; Forced; Variability

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.

近地表风控制着大气和下垫面之间的质量、能量和动量交换;它们影响地表温度和空气质量，是一种日益重要的能源;其极端情况对自然和建筑环境构成危害。拟议的研究由四个与风有关的互补研究项目组成，旨在解决该领域的紧迫问题。未来的气候变化将与风能和太阳能的变化（以及它们的协变，这可以减轻可再生能源的不稳定性）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世纪北美可再生能源相关的不确定性。我们还将把电力资源的年际和年代际变化与厄尔尼诺等主要气候变化模式联系起来。近地面风速由行星边界层（PBL）的过程决定。夜间边界层显示两种制度，具有非常不同的温度和风廓线。这些结构在天气和气候模型中表现不佳，导致温度和风的偏差。第二个项目将应用新的数学工具，以理想化的物理模型来研究这些制度。然后，我们将考虑不规则天气变化在驾驶状态转变中的作用。海面风分量的极值受其平均值波动的不对称性的影响很大。我开发了一套理想化的模型来解释这种行为。这些不对称的物理起源提供了一个新的视角的双谱，它划分成不同的频率贡献这种不对称。在第三个计画中，我们将利用双谱进一步探讨观测资料及理想模式中风分量脉动不对称性的物理现象。 天气和气候模式中的海气交换取决于风速。在这些模式中没有解决的小尺度风有助于通量增强，模式必须参数化。虽然参数化通常分配一个独特的亚网格尺度通量的解决流的每个独特的状态，我们已经表明，事实上，这些修正更好地表示概率分布。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，目标是在业务天气模式中实现这样的参数化。