CAREER: Departure from Monin-Obukhov Similarity Theory (MOST) using high-resolution turbulence models

湍流控制着热量、水分、空气和被动化学示踪剂（如二氧化碳）在陆地和大气之间流动的速率。准确的模式表示这种湍流通量从表面是必不可少的精确水文，天气和气候预测。我们目前的湍流通量的模型表示假设，大多数涡输运可以解释的本地观测和模型中的参数。然而，水平方向（例如，由于表面特性的变化）和垂直方向（由于涡流跨越异常大的垂直延伸）的变化可能使这些假设无效。在这个建议中，我们将使用高分辨率湍流模型和观测的组合来测试后一种效应。我们的主要目标是更好地解释最大的？最有效的？在我们的表面湍流交换的代表漩涡。这将最终改善我们测量地表通量并对其进行建模的方式。一个特别感兴趣的通量是蒸发（水分通量），它影响水文预报（如径流）以及天气和气候预测沿着。沿着这项研究活动，这项建议的主要教育目标之一是提供科学曝光，并鼓励在纽约哈莱姆的代表性不足的群体选择科学的职业和教育，通过科学演示和高中实习。目前大多数配方的表面湍流运输法是基于莫宁-奥布霍夫相似理论（MOST），这是基于当地的表面层缩放。这种理论近年来已被证明是有缺陷的。这种缺陷的主要原因之一是由于相干湍流结构的存在，其将湍流特性从边界层顶部向下传输到表面的大距离。这些结构不能很容易地观察到的时间平均涡度协方差技术，可能是在现场的表面能量收支，这是用来验证我们的陆面模式的非封闭的主要原因之一。为解决这些问题，本提案的研究目标是：i）使用直接数值模拟（DNS）和大涡模拟（LES）研究与边界层顶部的卷吸及其与表面湍流的相互作用有关的非局部输送的作用，ii）推导新的表面湍流定律和轮廓相似性，说明非局部输送的影响，iii）定义地面湍流通量涡动协方差观测的大涡动修正。（四）评价这些新公式在一个耦合的陆面和天气模式中的影响。a）发展国际学生交流项目，B）鼓励并建议代表性不足的群体参与STEM研究; c）开发课程（例如陆地-大气相互作用和湍流），对问题有一个面向多个科学界的广阔视野，以促进跨学科的合作和工作。

Turbulence controls the rate at which heat, moisture, air, and passive chemical tracers such as CO2 flow between the land and the atmosphere. Accurate model representation of such turbulent fluxes from the surface is essential for precise hydrologic, weather, and climate predictions. Our current model representation of turbulent fluxes assumes that most eddies transport can be explained by local observations and parameters in models. Nonetheless variability in the horizontal (e.g. due to variability in the surface characteristics) and in the vertical (due to eddies that span an unusually large vertical extend) directions can invalidate these assumptions. In this proposal we will test the latter effect using a combination of high-resolution turbulence models and observations. Our main objective is to better account for the largest ? most efficient ? eddies in our representation of turbulent exchange at the surface. This should ultimately improve the way we measure surface fluxes and model them. One flux of special interest is evaporation (the flux of moisture), which impacts hydrological forecasts (such as streamflow) along with weather and climate predictions. Along with this research activity, one of the main educational objectives of this proposal is to provide science exposure and encourage under-represented groups in Harlem, NY to choose scientific careers and education through science demonstrations and high-school internships.Most current formulations of the surface turbulent transport laws are based on Monin-Obukhov Similarity Theory (MOST), which is based on local surface layer scaling. This theory has been shown to be deficient in recent years. One of the main causes of this deficiency is due to the presence of coherent turbulent structures, which transport turbulent properties over large distances from the top of the boundary layer down to the surface. These structures cannot readily be observed by time-averaging eddy-covariance technique and may be one of the main reasons of non-closure of the in situ surface energy budget, which are used to validate our land-surface models. To address these issues, the research objectives of this proposal are to: i) Investigate the role of non-local transport related to the entrainment at the boundary layer top and its interaction with surface turbulence using Direct Numerical Simulations (DNS) and Large-Eddy Simulations (LES),ii) Derive new surface turbulent laws and profile similarity accounting for the effect of non-local transport, iii) Define large-eddy corrections for eddy-covariance observations of surface turbulent fluxes. iv) Evaluate the impact of these new formulations in a coupled land-surface and weather model.Consistent with this research activity, the educational objectives of the proposal are to: a) develop international student exchange programs, b) encourage and advise under-represented groups to participate in STEM research and c) develop classes (e.g. land-atmosphere interactions and turbulence) with a broad vision of the problem geared toward multiple scientific communities to facilitate cross-disciplinary collaborations and work.