RAPID: In-situ Observations to Characterize Multi-Scale Turbulent Atmospheric Processes Impacting Climate at Southern High Latitudes

科罗拉多大学、京都大学和东京国家极地研究所之间的这项国际合作将调查南极沿海大气湍流的来源。强迫地形的强风产生被称为大气重力波的波，当它们传播到更高的海拔时，它的幅度会增加，变得不稳定，破裂，并引起湍流。湍流的另一个来源是大气中的剪切层，在那里一层空气滑过另一层，导致开尔文-亥姆霍兹不稳定。总体而言，两者都在天气预报模式中准确表示南极气候方面发挥了重要作用。在这些遥远的南部高纬度地区收集新的湍流观测将改善对南极气候的风和温度预报。该项目将通过部署定制的高空气球系统与强大的遥感雷达和多个长时间气球在日本南极Syowa站的观测活动中的协调和协作来观测重力波和切变诱导的湍流动力学。这项研究的动机是这样一个事实，即代表真实的多尺度重力波(GW)阻力和开尔文-亥姆霍兹不稳定(KHI)动力学的源，以及它们对湍流输送/混合导致的动量和能量收支的贡献，在目前的通用环流模式(GCM)参数化方案中很大程度上缺失，导致南部高纬度天气尺度预报的降级。该项目利用高分辨率的现场湍流仪器来描述1)由katabatic强迫产生的地形GW，2)由低压天气尺度事件产生的非地形GW，以及3)在南极沿海地区各种尺度和背景环境中出现的KHI不稳定的大尺度动力学特征。该项目将在位于南极东部的日本Syowa站部署数十个配备定制现场湍流和无线电探空仪的低成本气球系统。气球有效载荷从20公里的最远点缓慢下降，以提供高分辨率、无尾迹的湍流观测，由Syowa的Pansy雷达提供部署指导，并与LODEWAVE长时间气球实验相协调。现场和遥感湍流观测的结合将量化与GWS和KHI有关的小尺度湍流大气过程的结构和动力学，这被认为在极地环境中普遍存在，但很少被观察到。在广泛的尺度和背景环境中测量的动量通量和湍流耗散率将提供数据集，以验证当前GCM对南部高纬度低层和中层大气GW阻力和湍流扩散系数的参数化，增加我们对这些过程及其对南极环流和气候的贡献的理解。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

This international collaboration between the University of Colorado, the University of Kyoto, and the National Institute of Polar Research in Tokyo, will investigate the sources of atmospheric turbulence in coastal Antarctica. Strong winds forced against terrain produce waves called atmospheric gravity waves, which can grow in amplitude as they propagate to higher altitudes, becoming unstable, breaking, and causing turbulence. Another source of turbulence is shear layers in the atmosphere, where one layer of air slides over another, resulting in Kelvin-Helmholtz Instabilities. Collectively, both play important roles in accurately representing the Antarctic climate in weather prediction models. Collecting new turbulence observations in these remote southern high latitudes will improve wind and temperature forecasts of the Antarctic climate. This project will observe gravity wave and shear-induced turbulence dynamics by deploying custom high-altitude balloon systems in coordination and collaboration with a powerful remote sensing radar and multiple long-duration balloons during an observational field campaign at the Japanese Antarctic Syowa station.This research is motivated by the fact that the sources representing realistic multi-scale gravity wave (GW) drag, and Kelvin-Helmholtz Instability (KHI) dynamics, along with their contributions to momentum and energy budgets due to turbulent transport/mixing, are largely missing in the current General Circulation Model (GCM) parameterization schemes, resulting in degraded synoptic-scale forecasts at southern high latitudes. This project utilizes high-resolution in-situ turbulence instruments to characterize the large-scale dynamics of 1) orographic GWs produced by katabatic forcing, 2) non-orographic GWs produced by low-pressure synoptic-scale events, and 3) KHI instabilities emerging in a wide range of scales and background environments in the coastal Antarctic region. The project will deploy dozens of low-cost balloon systems equipped with custom in-situ turbulence and radiosonde instruments at the Japanese Syowa station in Eastern Antarctica. Balloon payloads descend slowly from an apogee of 20 km to provide high- resolution, wake-free turbulence observations, with deployment guidance from the PANSY radar at Syowa, in coordination with the LODEWAVE long duration balloon experiment. The combination of in-situ and remote sensing turbulence observations will quantify the structure and dynamics of small-scale turbulent atmospheric processes associated with GWs and KHI, thought to be ubiquitous in polar environments but rarely observed. Momentum fluxes and turbulence dissipation rates measured over a wide range of scales and background environments will provide datasets to validate current GCM parameterizations for atmospheric GW drag and turbulence diffusion coefficients in the lower and middle atmospheres at southern high latitudes, increasing our understanding of these processes and their contribution to Antarctic circulation and climate.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.