Collaborative Research: Extensive Field Observations and Modeling to Understand Multi-band Precipitation Processes within Winter Storms

美国东北部的冬季风暴对社会和经济产生了广泛的影响，特别是在从马里兰州到马萨诸塞州人口稠密的沿海走廊沿线。被称为雪带的一组细长的、具有增强降雨率的特征通常出现在冬季风暴中，导致短距离内降雪积累的巨大变化。由于对雪带如何形成和维持的理解存在差距，对积雪的预测受到了阻碍。该项目将使用高空间和时间分辨率的观测和天气模型来解决更大风暴内产生雪带的过程。位于纽约长岛的一套研究仪器将每隔几分钟绘制一次3D风暴结构图。测量将解决雪粒在风暴中何时何地生长的问题。数值天气模型将研究与雪带形成相关的条件范围以及雪带形成时大气中各层的特征。这些发现可以帮助改进对降雪累积的预测，并将其应用于其他地理区域。这项工作将集中在雪带形成和维护的间歇性过程中。以前的工作表明，多个雪带的集合可以在很少或没有锋生的情况下发生，而且不稳定的存在并不能确定是否形成了雪带。此外，对雷达观测的分析没有显示出与积雪多波段锁定的清晰、持续的会聚特征，这意味着多波段在其整个生命周期中没有持续的上升气流。这项工作将解决重力波在小时间和空间尺度上帮助触发不稳定释放的作用，这些不稳定反过来又导致形成大多数中尺度雪带的非绝热反馈放大。该项目将使用一套水平和垂直扫描雷达、扫描激光雷达、额外的探空发射、高分辨率压力传感器和地表积雪图像来收集和分析高空间和时间分辨率的雪带观测。这些观测将允许在1公里的空间尺度和几分钟的时间尺度上检查所释放的不稳定性、动力学和微物理之间随时间的联合作用。该项目将使用建模来检查频带强迫和稳定相空间，使用一套大到大涡流尺度的理想化模拟。这项工作将提供对人口稠密的东北海岸温带气旋逗号头部内带状降水的更好理解。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。

Northeast U.S. winter storms have wide ranging societal and economic impacts, especially along the densely populated coastal corridor from Maryland to Massachusetts. Sets of long, thin features with enhanced precipitation rates called snowbands often occur within winter storms and contribute to large variations in snow fall accumulation over short distances. Forecasts for snow accumulation are hampered by gaps in understanding of how snowbands form and are maintained. The project will use high spatial and temporal resolution observations and weather models to resolve the processes within the larger storm that yield snowbands. A set of research instruments located on Long Island, NY will map the 3D storm structures every few minutes. Measurements will address where and when the snow particles grow in the storm. Numerical weather modeling will examine the range of conditions associated with snowband formation and the characteristics of layers in the atmosphere in which the snowbands occur. The findings can help improve forecasting of snowfall accumulation as well as be applied to other geographic regions. The work will focus on intermittent processes for snowband genesis and maintenance. Previous work showed that sets of multiple snowbands can occur with little or no frontogenesis, and the presence of instability did not determine whether bands formed. Additionally, analysis of radar observations did not show clear, sustained convergence signatures to be locked with snow multi-bands implying that multi-bands do not have sustained updrafts throughout their lifecycle. The work will address the role of gravity waves in helping to trigger the release of instabilities at small time and spatial scales that lead in turn to amplifying diabatic feedbacks that form the majority of mesoscale snowbands. The project will collect and analyze high spatial and time resolution observations of snowbands using a set of horizontal and vertical scanning radars, scanning LIDAR, additional sounding launches, high-resolution pressure sensors, and surface snow imagery. The observations will permit examination of the joint interactions over time among released instability, dynamics, and microphysics at spatial scales 1 km and time scales of a few minutes. The project will use modeling to examine the band forcing and stability phase space using a large suite of idealized simulations down to large-eddy scales. This work will provide an improved understanding of banded precipitation within the comma head of extratropical cyclones along the densely populated northeast coast.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.