Collaborative Research: Understanding the Influence of Turbulent Processes on the Spatiotemporal Variability of Downslope Winds in Coastal Environments

合作研究：了解湍流过程对沿海环境下坡风时空变化的影响

• 批准号: 2331728
• 负责人: Leila Carvalho
• 金额: $ 89.77万
• 依托单位: University of California-Santa Barbara
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2024
• 资助国家: 美国
• 起止时间: 2024-01-01 至 2026-12-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2331728&HistoricalAwards=false
• 关键词: Collaborative; Research; Understanding; Influence; Turbulent

Downslope windstorms in coastal terrain have resulted in many serious wildland fires. The overall conditions leading to those windstorms are well-known, however the details about the timing and severity of the winds are difficult to forecast due to a lack of knowledge about the small-scale mechanisms that drive the most severe winds in complex terrain. This award provides funding for the analysis and numerical modeling of data from the Sundowner Wind Experiment in the coastal Santa Barbara region of California. Sundowner winds are a specific type of downslope windstorm in the Santa Barbara area and they get their name from the tendency of the winds to strengthen into the evening and overnight hours. The research team plans a multi-faceted approach to provide societal benefits from this project, including working with the local National Weather Service office and Santa Barbara County Fire Department. Students will be involved with the project and outreach will be conducted at K-12 and community colleges in California and Virginia.The overarching goal of this project is to advance the understanding of interactions between downslope windstorms and upstream/downstream atmospheric boundary layer characteristics in coastal mountains by combining observations and numerical simulations. The Sundowner Winds Experiment (SWEX) was conducted from April 1 to May 15, 2022, in the coastal topography surrounding Santa Barbara, CA. Sundowner winds are a dry and gusty downslope wind on the southern facing slope of the Santa Ynez Mountains that can be associated with critical fire weather conditions. This project will use SWEX datasets and perform numerical simulations using the Weather Research and Forecasting model (WRF-km, 1.25km grid spacing) and Large Eddy Simulations (LES, 50m grid spacing) to improve the understanding of mechanisms associated with lee slope jets and near-surface wind variability. The research team will also investigate biases in WRF-km simulations. Three main objectives are targeted:1) Identify mechanisms responsible for the spatiotemporal variability of lee slope wind structure during Sundowners and quiescent periods using SWEX observations.2) Examine the skill of WRF-km in representing lee slope wind structure and identify relevant processes contributing to model biases.3) Investigate the performance of LES at 50m grid spacing in representing lee slope wind structure, and the contribution of turbulent processes to biases in simulated surface winds.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

沿海地形的下坡风暴导致了许多严重的荒地火灾。 导致这些风暴的总体条件是众所周知的，但由于缺乏对在复杂地形中驱动最猛烈风力的小规模机制的了解，因此很难预测有关风力的时间和严重程度的详细信息。 该奖项为加利福尼亚州圣巴巴拉沿海地区日落风实验数据的分析和数值建模提供资金。 日落风是圣巴巴拉地区一种特殊类型的下坡风暴，因风在傍晚和夜间增强的趋势而得名。 研究团队计划采取多方面的方法来从该项目中提供社会效益，包括与当地国家气象局办公室和圣巴巴拉县消防局合作。 学生将参与该项目，并在加利福尼亚州和弗吉尼亚州的 K-12 和社区大学进行推广。该项目的总体目标是加深对沿海地区下坡风暴与上下游大气边界层特征之间相互作用的理解通过结合观测和数值模拟来识别山脉。 日落风实验 (SWEX) 于 2022 年 4 月 1 日至 5 月 15 日在加利福尼亚州圣巴巴拉周围的沿海地形进行。 日落风是圣伊内斯山脉南坡的干燥阵风下坡风，可能与严重的火灾天气条件有关。 该项目将使用 SWEX 数据集，并使用天气研究和预报模型（WRF-km，1.25km 网格间距）和大涡模拟（LES，50m 网格间距）进行数值模拟，以加深对与背风坡急流和近地表风的变化。 研究小组还将调查 WRF-km 模拟中的偏差。 实现了三个主要目标：1) 使用 SWEX 观测确定日落和静止期间背风坡风结构时空变化的机制。2) 检查 WRF-km 表示背风坡风结构的技能，并确定导致3) 研究 LES 在 50m 网格间距下代表背风坡风结构的性能，以及湍流过程对模拟表面风偏差的贡献。该奖项反映通过使用基金会的智力价值和更广泛的影响审查标准进行评估，NSF 的法定使命被认为值得支持。