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

本研究包括三个独立但紧密耦合的目标：第一个目标是利用系留提升系统（TLS），结合大型合作实验CASES-99期间并发的55米塔数据和相关数据集，分析温度、风和湍流耗散率的高分辨率垂直剖面。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，将湍流耗散率的TLS曲线与塔架上获得的垂直速度变化曲线进行比较。如果这种比较在大多数夜间条件下是成功的，它将能够确定SBL的混合高度（MH），即使MH远高于塔的高度。将使用其他塔/TLS测量进行可比研究。第二个目标是在五个独立的CASES-99夜晚进行的40多个小时的观测中，检查残余层的精细尺度风速、风向、温度和湍流结构。在这些时期，SBL的结构从传统的到薄传统的，并且包含至少一个晚上，当SBL可以被归类为倒置的。将证明RL不符合目前的观点，即它是一个静态稳定的温度剖面和最小湍流活动的区域，它仅仅是前一天对流边界层的被动残余。相反，它将证明RL是一个非常动态的、复杂的区域，具有显著的风切变、温度梯度、湍流结构，偶尔还有明显的重力波活动。更重要的是，它将表明，在非常小的高度范围内，在几十分钟的时间尺度上，小尺度湍流的垂直剖面经常表现出极端的强度变化（超过两个数量级）。这些增强的湍流区域，即使在当地午夜之后，有时也可以与地面的夜间水平相媲美，并且可能对RL和SBL之间的垂直输送产生重大影响。第三个也是最终的目标是将上述概念纳入当前的SBL和RL模型中，以提高对上层SBL动力学和SBL/RL相互作用的理解。在这项工作中，重点将放在建模早晨的过渡，以及它是如何受到前一晚RL过程的影响。虽然很难将本研究的某些方面直接纳入单列模型，但作为比较模型导出量与测量量的一种手段，结果应该证明是非常宝贵的，以便能够理解所研究过程的重要性和敏感性。在智力上，上述活动将为整个SBL和RL的复杂动态过程的理论/建模社区提供重要的新信息。在更广泛的范围内，预期的结果将为RL的远距离污染运输提供有价值的新见解，并阐明两个地区之间尚未解释的零星耦合。这些努力的结果将为设计今后的实地活动提供有用的框架。最后，博士后候选人将学习在建模和观测研究领域工作，这对未来在该领域的成功非常重要。

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.