Boundary-Layers of the Cold and Dark Atmospheres

该奖项旨在研究阿拉斯加极端冬季寒冷和黑暗大气中的大气边界层。阿拉斯加边界层发展的严格辐射和大气流动条件对我们的实验和建模方法的研究都提出了挑战。在如此严酷的冬季条件下，该项目将进行实地密集实验，利用地面、遥感和现场无人驾驶飞机系统记录辐射、湍流、成分和动力学。该研究将结合一系列观测和中尺度/微尺度模拟，促进我们对辐射驱动边界层中发生的物理过程的理解。研究的影响是为了提高对冬季极地地区空气污染、气象预报和区域气候产品的了解。具体而言，该项目侧重于了解地表辐射冷却、地表不均匀性、大气成分和热力学如何导致特定的边界层湍流和动态状态，以及它们如何在中尺度模式中表示。本项目将重点关注以下物理过程：(1)反气旋停滞天气条件下浅层地面逆温层的形成和破裂；(2)反气旋和向气旋过渡条件下的边界层行为，包括地面逆温层和高空天气逆温层，它们的辐射耦合及其对地面湍流的反馈作用；3)边界层动力和湍流状态（垂直和水平）在浅层冷流的存在下控制混合和输运，从而导致瞬态边界层状态。实验数据集的独特之处在于，目前模式中的地表参数化并没有完全考虑到在气象框架和条件下所指示的机制和相互作用。在极地大气的严格条件下，需要推进对颗粒物质和气体的化学和微物理学的理解，这一点突出了这项研究的重要性。空气污染产品的物理和化学转化所固有的是我们基于地面或机载观测平台（IGAC-ALPACA野外实验）将污染源与受体连接起来的能力。该项目填补了这一特定空白，提供关键观测、中尺度建模评估和模型验证，以改善导致极端边界层状态的物理过程的模型表示。同样，改进地面风和气温的预报以及推进极地大气的高分辨率气候产品，都需要更好地表示辐射边界层。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

This award is to investigate atmospheric boundary layers in the cold and dark atmospheres of the extreme Alaskan winters. The stringent radiation and atmospheric flow conditions in which the Alaskan boundary layer develops challenge our research in both experimental and modeling approaches. In such harsh winter conditions, the project will conduct a field intensive experiment to document radiation, turbulence, composition and dynamics using surface, remote sensing and in-situ unmanned aircraft systems. The research will advance our understanding of physical processes taking place in radiative-driven boundary layers combining the set of observations with mesoscale/microscale modeling. Research impacts are geared towards improving understanding of air pollution, meteorological forecasting and regional climate products in polar regions during winters.In specific, the project focuses on understanding how outstanding surface radiative cooling, surface inhomogeneity, atmospheric composition and thermodynamics result in specific boundary-layer turbulent and dynamic states and how they are represented in mesoscale models. This project will focus on the following physical processes: 1) the buildup and breakup of shallow-stratified surface-based temperature inversion layers during stagnant anticyclone synoptic conditions, 2) the boundary-layer behavior including surface-based temperature inversion layer and elevated synoptic temperature inversion layers during anticyclone and transitions to cyclone conditions, their radiative coupling and their feedback effects on the surface turbulence, and 3) the boundary-layer dynamic and turbulent regimes (vertical and horizontal) in the presence of shallow cold flows controlling mixing and transport resulting on transient boundary-layer states. The experimental datasets are unique in the sense that current surface parameterizations in models do not fully account for the indicated mechanisms and interactions in the meteorological framework and conditions. The importance of this research is highlighted by the need to advance understanding of the chemistry and microphysics of particulate matter and gases in the stringent conditions of the polar atmospheres. Inherent to the physical and chemical transformations of air pollution products is our ability to connect sources to receptors based on ground based or airborne observational platforms (IGAC-ALPACA field experiment). This project fills this specific gap providing critical observations, mesoscale modeling assessment and model validation to improve model representation of physical processes leading to extreme boundary-layer states. Similarly, improving forecasting of surface winds and air temperatures and advancing high resolution climate products in polar atmospheres requires a better representation of radiative boundary-layers.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.