Collaborative Research: SAVANT--Stable Atmospheric Variability ANd Transport

稳定边界层(SBL)尽管经常出现，但在大气模拟中仍然是一个相对有问题的组成部分。虽然普遍认为Monin-Obukov相似理论由于非均匀非定常流动而不适用于SBL，但对于SBL还没有提出通用的组织理论。这在研究气溶胶运动作为大气动力学的函数时提出了一个问题。众所周知，稳定的空气层结导致了卡塔式下坡风，即使在非常浅的地形上也是如此。这些下坡风可以与背景流汇合，并假设这种汇聚为特定事件提供了起点，例如内部重力波(IGW)。尽管稳定的边界层通常较浅，但重力内波可以与水平面成一定角度传播，并修改局部切变，从而在空间产生周期性的湍流混合。很少有研究在低起伏的地形地区研究这一点。该项目将采取措施解决这些尚未解决的问题。该项目的主要目标是量化浅层冷空气排放对气溶胶输送和扩散的影响。虽然测量活动将产生丰富的数据集，但这里的研究将重点回答以下问题：1.在什么中、微尺度条件(即云量、临界风速、地表覆盖、稳定状况、背景流、坡率和长度、沟谷体积)下存在收敛流？2.收敛流产生的湍流强迫振荡和/或重力波的时空尺度是什么，这些振荡/重力波是否遵循IGW的线性理论？3.湍流强迫振荡和/或汇流产生的重力波如何影响气溶胶的扩散和输送？这项工作的新方面是能够利用气溶胶激光雷达识别湍流事件和特征，从而为我们目前的理解增加缺失的空间分量。智力价值：该项目将提供关于排水和汇聚流动及其对低地形变异性地区气溶胶输送的影响的新知识。尤其令人感兴趣的是云量、临界风速、湍流间歇性、地形和稳定状况如何影响流动和气溶胶输送。该项目将填补目前SBL中流动和运输的模型参数化方面的重大空白。它将提供新的参数化和修改，以扩展现有的SBL理论。该项目还将确定由此产生的分散与融合事件强度之间的经验关系。广泛的影响：科学上更广泛的影响将包括丰富的数据集以及定义可能发生融合的时间和地点的经验关系。这些可以在目前缺少这些关系的预测模型中进行调整。对社会更大的好处是向研究人员和那些对预测危险排放的影响感兴趣的研究人员提供丰富的现场数据集。除了科学探究的这一内在好处外，这项工作还将寻求扩大公众对科学探究性质的了解，并特别侧重于仪器。该项目将创建一系列视频模块，用于传统气象学课程无法提供的本科生课程和公共教育。

Stable boundary layers (SBL) are still a relatively problematic component of atmospheric modeling, despite their frequent occurrence. While general agreement exists that Monin-Obukov similarity theory is not applicable in the SBL due to the non-homogeneous and non-stationary flow, no universal organizing theory for the SBL has been presented. This poses a problem when examining aerosol movement as a function of atmospheric dynamics. It is known that stable air stratification results in katabatic downslope winds, even in very shallow topographic airsheds. These downslope winds can converge with background flow, and it is hypothesized that this convergence provides a starting point for specific events, such as internal gravity waves (IGW). Even though the stable boundary layer is normally shallow, internal gravity waves can propagate at an angle from the horizontal plane, and modify local shear, thus generating periodic turbulent mixing in space. Few studies have examined this in low relief topographic areas. This project will conduct measurements to address these open issues. The major objective of the project is to quantify the effects of shallow cold air drainage on aerosol transport and dispersion. While the measurement campaign will result in a rich dataset, the research here will focus on answering the following questions:1.Under what mesoscale and microscale conditions (i.e. cloud cover, threshold wind speed, surface cover, stability regime, background flow, slope ratio and length, and gully volume) do converging flows exist?2.What is the spatial and temporal scale of turbulence forced oscillations and/or gravity waves generated by converging flows, and do these and do these oscillations/gravity waves follow the linear theory of IGW?3.How are aerosol dispersion and transport influenced by turbulence forced oscillations and/or gravity waves generated from a converging flow?The novel aspect of this work is the ability to identify turbulent events and features with aerosol lidars to add the missing spatial component to our current understanding.Intellectual Merit:The project will provide new knowledge on drainage and converging flows and their effects on aerosol transport in areas of low topographic variability. Especially of interest is how cloud cover, threshold wind speed, turbulence intermittency, topography, and stability regime affect the flows and aerosol transport. This project will fill the significant gaps in current model parameterizations of the flows and transport in SBL. It will provide new parameterizations and modifications to extend existing to the SBL theories. The project will also identify an empirical relationship between this resulting dispersion and the intensity of the convergence event.Broader Impacts:Scientific broader impacts will include a rich dataset as well as empirical relationships defining when and where convergence is likely to occur. These can be adapted in forecast models that are currently missing these relationships. The larger benefits to society are to a rich field data set to researchers interested in microscale meteorological impacts on agricultural crop security and those interested in predicting impacts of hazardous releases. In addition to this intrinsic benefit of scientific enquiry, the work will also seek to expand public knowledge in understanding the nature of scientific enquiry with a specific focus on instrumentation. The project will create a series of video modules for use in undergraduate classes and public education where traditional meteorology programs are not available.