Developing Improved Models of the Stable Boundary Layer Incorporating the Residual Layer Region

开发包含残余层区域的稳定边界层的改进模型

• 批准号: 0631966
• 负责人: Ben Balsley
• 金额: $ 45万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2011-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0631966&HistoricalAwards=false
• 关键词: Developing; Improved; Models; Stable; Boundary

This research consists of three separate, but closely coupled objectives: The first objective is to analyze high-resolution vertical profiles of temperature, wind, and turbulence dissipation rate using the tethered lifting system (TLS) in conjunction with concurrent 55-m tower data and related data sets during CASES-99, a large cooperative experiment to observe boundary layer processes. The work will establish the capability of the TLS to extend some of the tower observations through the stable boundary layer (SBL) and well into the so-called residual layer (RL). To provide one important example, TLS profiles of the turbulence dissipation rate will be compared with tower-obtained vertical velocity variance profiles. If this comparison is successful under most nighttime conditions, it will enable a determination of the mixing height (MH) of the SBL, even though the MH lies well above tower heights. Comparable studies using other tower/TLS measurements will be conducted.The second objective is to examine fine-scale wind speed, wind direction, temperature, and turbulence structure in the residual layer during over forty hours of observations obtained over five separate CASES-99 nights. The SBL structure during these periods ranged from traditional, through thin-traditional, and contained to at least one night when the SBL could be classified as upside down. It will be demonstrated that the RL does not fit the current view that it is a region of statically stable temperature profiles and minimal turbulence activity, and that it is merely a passive remnant of the previous day's convective boundary layer. Rather, it will be demonstrated that the RL is a very dynamic, complex region with significant wind shears, temperature gradients, turbulence structure, and, on occasion, pronounced gravity wave activity. More significantly, it will be shown that the vertical profiles of small-scale turbulence often exhibit extreme intensity variations (more than two orders of magnitude) over very small altitude ranges, and on time scales of a few tens of minutes. These enhanced turbulence regions, even after local midnight, can, on occasion, be comparable to nighttime levels at the surface, and could have a significant impact on vertical transport between the RL and SBL.The third and ultimate objective is to incorporate the above concepts into current models of both the SBL and the RL in order to improve understanding of both upper level SBL dynamics and SBL/RL interactions. In this work, the focus will be on modeling the morning transition and how it is impacted by processes in the RL during the preceding night. Although it would be difficult to directly include some aspects of this research into single column models, the results should prove invaluable as a means of comparing model-derived quantities with measured quantities to be able to understand the importance of and sensitivity to the studied processes.Intellectually, the above activities will provide critical new information for the theoretical/modeling communities on complex, dynamical processes throughout the SBL and well into the RL. On a broader scale, the anticipated results will provide valuable new insight into long-distant pollution transport in the RL and illuminate the as-yet unexplained, sporadic coupling between the two regions. Results from these efforts will provide a useful framework for designing future field campaigns. Finally, the post-doctoral candidate will learn to work in both modeling and observational research arenas, which is very important for future success in this field.

本研究包括三个独立的，但密切相关的目标：第一个目标是分析高分辨率的温度，风和湍流耗散率的垂直廓线使用系留升力系统（TLS）结合并发的55米塔数据和相关数据集在CASES-99，一个大型的合作实验，观察边界层过程。这项工作将建立TLS的能力，通过稳定边界层（SBL）和所谓的剩余层（RL）扩展一些塔观测。为了提供一个重要的例子，湍流耗散率的TLS剖面将与塔获得的垂直速度方差剖面进行比较。如果这种比较在大多数夜间条件下是成功的，则它将能够确定SBL的混合高度（MH），即使MH远高于塔高度。第二个目标是在五个独立的CASES-99个夜晚获得的四十多个小时的观测期间，检查细尺度风速、风向、温度和剩余层中的湍流结构。在这些时期的SBL结构范围从传统的，通过薄传统，并包含至少一个晚上时，SBL可以被归类为颠倒。它将被证明，RL不适合目前的观点，它是一个静态稳定的温度廓线和最小的湍流活动的区域，它只是一个被动的残余前一天的对流边界层。相反，它将被证明，RL是一个非常动态的，复杂的区域与显着的风切变，温度梯度，湍流结构，有时，显着的重力波活动。更重要的是，它将表明，小尺度湍流的垂直廓线往往表现出极端的强度变化（两个数量级以上）在非常小的高度范围内，并在几十分钟的时间尺度。这些增强的湍流区域，即使在当地午夜，有时，可以在表面的夜间水平相媲美，并可能有一个显着的影响RL和SBL之间的垂直运输。第三个和最终的目标是将上述概念纳入目前的模型都SBL和RL，以提高高层SBL动力学和SBL/RL的相互作用的理解。在这项工作中，重点将是对早晨过渡进行建模，以及它如何受到前一天晚上RL过程的影响。虽然很难将本研究的某些方面直接纳入单柱模型，但结果应证明是非常宝贵的，因为可以将模型导出的量与测量的量进行比较，从而能够理解所研究过程的重要性和敏感性。整个SBL和RL中的动态过程。在更广泛的范围内，预期的结果将提供有价值的新的见解，在RL的远距离污染传输，并阐明了尚未解释的，零星的两个地区之间的耦合。这些努力的结果将为设计今后的实地运动提供一个有用的框架。最后，博士后候选人将学习在建模和观测研究领域工作，这对该领域未来的成功非常重要。