Common Variability in the Stable Atmospheric Boundary Layer on Small Space and Time Scales

小时空尺度上稳定大气边界层的常见变化

基本信息

批准号：
1945587
负责人：
Larry Mahrt
金额：
$ 55.07万
依托单位：
NorthWest Research Associates, Incorporated
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2020
资助国家：
美国
起止时间：
2020-01-15 至 2023-12-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1945587&HistoricalAwards=false
关键词：
Common Variability Stable Atmospheric Boundary

项目摘要

A regular nighttime occurrence is the development of a stable boundary layer, which is a shallow, near-calm layer of air near the Earth’s surface. However, despite the air seemingly being calm, there are ongoing motions which have important impacts on near-ground temperatures and the dispersion of pollutants. This research award provides support for the analysis of existing observational data on stable boundary layer motions, with a fresh look at how they can be tracked and how that information can be used to improve numerical weather models. A specific use case that this award will address, in consultation with local field managers, is vineyards in the Pacific Northwest where frosts and freezes have a significant impact.The research under this award will expand understanding of small-scale, non-stationary motions, their interaction with surface heterogeneity, and their stochastic behavior. The focus is on submeso motions, which are formally defined to include motions on scales just larger than the largest turbulent eddies and up to scales normally considered to be the smallest mesoscale motions (2km). A sequence of case studies of different types of small-scale motions will be constructed using data from 9 prior field campaigns and a package of different analysis methods that has been developed by the researcher. The main objectives of the proposal are to: 1) Quantify the submeso time and space variability of the temperature, the wind vector, and turbulent fluxes and relate these variations to the forcing variables, 2) Track propagating modes across networks of data and examine their interaction with surface-based phenomena due to gentle topography and the impact of this interaction on turbulent fluxes, 3) Formulate probability distributions for short-term (non-turbulent) variations of the temperature and wind direction for low wind speeds and relate the characteristics of the distributions to the forcing variables, and 4) Reanalyze the behavior of the fluxes and corresponding transfer coefficients in the bulk formula for low wind speeds based on time averaging and based on spatial averaging across the networks and improve formulation of the transfer coefficients for low wind speeds.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.

夜间经常发生的是稳定边界层的形成，这是靠近地球表面的浅层、近乎平静的空气层。然而，尽管空气看似平静，但持续的运动对近地面产生了重要影响。该研究奖项为分析稳定边界层运动的现有观测数据提供了支持，并重新审视了如何跟踪这些数据以及如何使用这些信息来改进数值天气模型。该奖项的用例将与当地现场管理人员协商，解决霜冻和冰冻对太平洋西北地区的葡萄园产生重大影响的问题。该奖项的研究将扩大对小规模非平稳运动及其与表面异质性相互作用的理解，以及重点是亚细观运动，其正式定义为包括比最大湍流涡流更大的尺度上的运动，以及通常被认为是最小的中尺度运动（2km A）的尺度。将使用之前 9 次现场活动的数据和研究人员开发的一系列不同分析方法来构建不同类型小规模运动的案例研究序列。该提案的主要目标是：1）量化。温度、风矢量和湍流通量的亚细观时间和空间变化，并将这些变化与强迫变量联系起来，2) 跟踪数据网络中的传播模式，并检查由于平缓的地形和影响它们与地表现象的相互作用这次互动的湍流通量，3) 制定低风速下温度和风向的短期（非湍流）变化的概率分布，并将分布特征与强迫变量联系起来，以及 4) 重新分析通量的行为以及基于时间平均的低风速批量公式中相应的传递系数，并反映整个网络的空间平均，并改进低风速传递系数的公式。该奖项是 NSF 的法定使命，并已被通过使用基金会的智力优点和更广泛的影响审查标准进行评估，认为值得支持。