Collaborative Research: An Observational, Modeling, and Climatological Study of Sierra Rotors

合作研究：Sierra Rotors 的观​​测、建模和气候学研究

• 批准号: 0242980
• 负责人: Dale Durran
• 金额: $ 17.22万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-05-01 至 2007-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0242980&HistoricalAwards=false
• 关键词: Collaborative; Research; Observational; Modeling; Climatological

This research is focused on a study of mountain-wave induced rotors in the lee of the Sierra Nevada. Rotors are intense low-level horizontal vortices that form along an axis parallel to and downstream of a mountain crest. While they are known to be very hazardous to aviation, there have been few quantitative observational and theoretical studies of this phenomenon. As a result, understanding of rotor structure and rotor dynamics is relatively incomplete, and the ability to forecast rotors shows little skill.This study will be conducted using observations and numerical simulations. The observations will be collected in and upstream of the Owens Valley, which lies directly to the east of the southern Sierra Nevada. The eastern slopes of the southern Sierra Nevada are the tallest, steepest quasi-linear topographic barrier in the contiguous United States. The westerly winds that blow across the Sierra Nevada frequently generate large-amplitude mountain waves and strong rotors over the Owens Valley.Two major objectives of this project are to: (1) establish quantitative characteristics of the rotor behavior including the location and the frequency distribution of the rotor-inducing mountain-wave events, and (2) evaluate the extent to which current operational mesoscale models can reliably forecast the occurrence of rotors. The first major objective will be accomplished with a small field experiment involving the installation of an array of automatic weather stations and wind profilers in the Owens Valley and radiosonde launches to sample the upstream flow. The numerical modeling effort in support of the second objective is designed to determine whether deficiencies in the model forecasts (as revealed by comparison with the observational data) are due to an inadequate representation of the large-scale flow striking the mountains or to difficulties in the detailed computation of the mountain waves and rotors themselves.The results of this project will serve as a basis or improving the forecasting capability of numerical models applied to steep topography. One consequence of such improvement would be to provide better forecasts of severe aviation hazards in mountainous terrain.

这项研究的重点是对内华达山脉Lee的山波诱发转子的研究。 转子是强烈的低级水平涡旋，沿着平行于山顶的轴线形成轴。 虽然众所周知，它们对航空非常有害，但对此现象的定量观察和理论研究很少。 结果，对转子结构和转子动力学的理解相对不完整，并且预测转子的能力显示几乎没有技巧。这项研究将使用观测和数值模拟进行。 这些观察结果将在欧文斯山谷的上游收集，直接位于内华达山脉南部的东部。 内华达山脉南部的东坡是美国连续美国最高，最陡峭的准线性地形屏障。 内华达山脉吹来的西风经常在欧文斯山谷上产生大幅度的山浪和强大的转子。该项目的两个主要目标是：（1）建立转子行为的定量特征，包括位置和频率分布，以及诱导转子的山脉事件的频率分布，以及（2）对当前模型进行范围的范围，可以相互依赖的范围。 第一个主要目标将通过一个小型实验实现，涉及在欧文斯山谷（Owens Valley）和Radiosonde发射中安装一系列自动气象站和风能投影仪，以采样上游流量。 旨在确定模型预测中的缺陷（如与观测数据相比所揭示的）是由于触及山脉的大规模流动不足的代表不足或在登台模型的详细计算中，该项目的详细计算会导致数值模型的努力是由于模型预测中的缺陷是由于对山脉的大规模流量的代表不足而导致的。地形。 这种改善的结果是，在山区的严重航空危险中提供更好的预测。