Collaborative Research: Sundowner Winds EXperiment (SWEX) in Santa Barbara, California

合作研究：加利福尼亚州圣巴巴拉的日落风实验 (SWEX)

• 批准号: 1921504
• 负责人: Stephan De Wekker
• 金额: $ 31.59万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-01-01 至 2025-06-30
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1921504&HistoricalAwards=false
• 关键词: Collaborative; Research; Sundowner; Winds; EXperiment

Wildfires are among the greatest natural hazards in the Western U.S. and other parts of the world. The numerous tragic events in recent years in California have exposed the great vulnerability of the population to wildfires and the critical need to improve understanding and enhance predictability of windstorms in complex terrain. Coastal Santa Barbara County (SB), with a population exceeding 130,000 inhabitants, is among the most exposed communities to wildfire hazards in southern California. The Santa Ynez Mountains rise abruptly from coastal SB separating the Pacific Ocean on its south face from the Santa Ynez Valley on its north face. Downslope, dry and gusty windstorms are frequently observed on the southern-facing slopes of the Santa Ynez Mountains. These winds typically intensify around sunset and throughout the night, and are known as "Sundowner winds" or "Sundowners". They are considered the most significant fire-weather regime in coastal SB and pose hazardous conditions to aviation. They have enhanced the severity of all major wildfires affecting the SB coastal population. Therefore, improved weather warnings and forecast lead time, including spatiotemporal specificity of where winds will be strongest, are critical to increase resilience to wildfires. Sundowners exhibit large spatiotemporal variability and are driven by unique complex mechanisms. The Sundowner Winds Experiment (SWEX) will investigate these unique aspects of Sundowners to advance the understanding and predictability of these winds, while providing rich data sets for developing new theories of downslope windstorms in coastal environments with similar geographic and climatic characteristics. This will be accomplished with strategic meteorological observations of the atmospheric processes hypothesized to modulate Sundowner winds intensity and spatial variability. These results will significantly contribute to improve the predictability of windstorms in complex terrain in coastal environments, with significant impacts to large communities living in fire prone areas. The project will provide key outreach materials for dissemination to government agencies and the media and will educate the public about fire weather and natural disasters. Moreover, the project will support the development of new educational courses, and the training of undergraduate and graduate students, including minorities, in six universities in the U.S. Sundowners spatiotemporal characteristics are controlled by complex interactions between atmospheric processes occurring upstream, in the Santa Ynez Valley and San Rafael Mountains, and downstream due to the influence of a cool and stable marine boundary layer. The SWEX campaign is designed to enhance spatial measurements to resolve local circulations and vertical profiles from the boundary layer to the mid-troposphere, and from the SB channel to the Santa Ynez Valley. These observations will be used to test hypotheses concerning the mechanisms controlling Sundowner winds, evaluate mesoscale simulations and improve lead time forecasts of Sundowners. More specifically, the multi-sensor platforms and aircraft will be utilized to investigate how the structure and dynamics of the marine and continental Boundary Layers (BL) influence mountain flows during Sundowners and undisturbed periods, including intensity, timing and geographic characteristics of downslope winds, temperatures and humidity. These measurements will enable to examine underlying mechanisms relating high amplitude mountain waves, critical layers, and surface wind intensity leeward of the Santa Ynez Mountains. These observations will be utilized to investigate how variations in BL structure and tropospheric stability control mountain wave flows and the lee-slope jet, and the importance of these mechanisms for the predictability of Sundowner winds. SWEX brings cutting-edge science, the state-of-art facilities at National Center for Atmospheric Research and multiple instrumental platforms to bear on this important problem. It will build linkages with those responsible for predictions and fire response in a region that is representative of many areas with similar vulnerabilities. SWEX will improve the capability of the National Weather Service to forecast weather hazards in the Los Angeles area, specifically in coastal SB. Thus this project has substantial broader impacts.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.

野火是美国西部和世界其他地区最大的自然灾害之一。近年来在加州发生的众多悲剧事件暴露了人们对野火的极大脆弱性，以及改善对复杂地形中风暴的理解和提高其可预测性的迫切需要。沿海圣巴巴拉县（SB）人口超过13万，是加州南部最容易遭受野火危害的社区之一。圣伊内斯山脉从海岸SB突然升起，将其南面的太平洋与北面的圣伊内斯山谷分开。在圣伊内斯山脉面向南的山坡上经常观察到下坡、干燥和阵风风暴。这些风通常在日落前后和整个晚上增强，被称为“日落风”或“日落风”。它们被认为是沿海SB中最重要的火灾天气状况，并对航空构成危险。它们增强了影响SB沿海人口的所有主要野火的严重性。因此，改进天气警报和预报提前时间，包括风最强的时空特异性，对于提高对野火的抵御能力至关重要。日落具有很大的时空变异性，并由独特的复杂机制驱动。日落风实验（SWEX）将研究日落风的这些独特方面，以促进对这些风的理解和可预测性，同时为在具有相似地理和气候特征的沿海环境中开发下坡风暴的新理论提供丰富的数据集。这将通过对大气过程的战略气象观测来实现，这些大气过程被假设为调节日落风强度和空间变异性。这些结果将大大有助于提高沿海环境复杂地形中风暴的可预测性，对生活在火灾易发地区的大型社区产生重大影响。该项目将提供关键的外联材料，分发给政府机构和媒体，并将教育公众了解火灾天气和自然灾害。此外，该项目将支持开发新的教育课程，并在美国的六所大学培训本科生和研究生，包括少数民族。SWEX活动旨在加强空间测量，以解析从边界层到对流层中部以及从SB通道到Santa Ynez山谷的局部环流和垂直廓线。这些观测结果将用于检验有关控制日落风的机制的假设，评估中尺度模拟和改进日落的提前期预报。更具体地说，多传感器平台和飞机将用于研究海洋和大陆边界层（BL）的结构和动力学如何影响日落和未受干扰期间的山流，包括下坡风的强度，时间和地理特征，温度和湿度。这些测量将能够检查相关的高振幅山波，临界层，和表面风强度背风的圣伊内斯山脉的基本机制。这些观测结果将被用来研究如何在BL结构和对流层稳定性的变化控制山波流和背风坡喷流，以及这些机制的重要性的可预测性的日落风。SWEX带来了尖端的科学，国家大气研究中心的最先进的设施和多个仪器平台来解决这个重要的问题。它将与该区域负责预测和火灾反应的人员建立联系，该区域代表着许多具有类似脆弱性的地区。SWEX将提高国家气象局预测洛杉矶地区，特别是沿海SB地区天气灾害的能力。因此，该项目具有实质性的广泛影响。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。