Collaborative Research: Observations and Modeling of Mesoscale Precipitation Banding in Cool-season Storms

改进对温带气旋降水的预报需要继续整合观测和模式，以了解与降水带有关的演变和过程。美国东北部气旋逗号部分的中尺度带已被记录为引起局地强降水率和降水量。在中层锋生和稳定性降低的情况下，逗号头内主带的生命周期和微物理特性已被记录下来，但对多带风暴的研究较少。潜在的假设是，许多与冬季风暴相关的定量降水预报（QPF）误差是由于模式在预测这些多波段时存在困难，因为它们的空间尺度较小，对流特征较多，并且它们向单个波段的高级增长。该小组将整合建模和观测研究，以了解美国东北部温带气旋降水特征的频谱。使用来自wsr - 88d的约20年的雷达数据，主要机场几年的终端多普勒天气雷达（TDWR），高空探测，垂直指向雷达观测，disdmeter和多角度雪花相机（MASC）在长岛NY Stony Brook，以及高分辨率网格分析和天气研究与预报（WRF）预测来表征带状降水和冰的微物理特性，并评估模型输出。目标是表征气旋周围的带状细胞和带状的生命周期和轨迹，并量化相对于其他降水特征的多带状结构对风暴降水积累的重要性。我们还将确定需要哪一组参数来实际模拟多带状降水。我们的工作将通过一系列历史运行和敏感性研究来解决冰微物理和带状降水中尺度可预测性的参数化问题。知识优势：在寒冷季节，QPF的改善继续滞后于我们预测冬季风暴中的压力和位势高度场的能力。该奖项将通过使用基于特征的跟踪算法完成美国东北部地区带状和细胞的发生、增长和衰减的综合气候学，从而提高对中纬度气旋逗号头部降水特征谱的理解。到目前为止，还没有针对中纬度气旋周围多波段发生和演化的实际案例进行建模研究，并且在所有波段尺度上的微物理验证也很有限。这项工作将提供对带状降水的更好理解，这可以应用于逗号头内带的其他区域。我们基于地面的微物理工作将评估和改进我们新的微物理参数化，重点是改进模型内的边缘表示。更广泛的影响：美国东北部的主要冬季风暴具有广泛的社会和经济影响。纽约市大都市区拥有近2000万人口，是东海岸的主要交通枢纽。近年来，该地区遭受了几次大风暴的袭击（http://www.nyc.gov/html/oem/html/hazards/winter_history.shtml）。该项目的结果将有助于改进预报员用于预测逗号头部带状降水的现有概念模型，并改进中尺度模式中的QPFs。Colle博士和Yuter博士每年将各自资助一名研究生。几名本科生研究助理也将接受数据处理和分析方面的培训。他们的研究成果将由学生们作为海报展示在研究研讨会上，比如每年春夏由NCSU和Stony Brook举办的研讨会。研究结果也将在会议报告和期刊文章中传播。此外，Yuter博士计划在北卡罗来纳当地的科学博物馆举办一些关于雪和冬季风暴的普通观众讲座。

Improved forecasting of precipitation within extratropical cyclones requires continued integration of observations and models to understand the evolution and processes associated with precipitation bands. Mesoscale banding within the comma-head portion of Northeast U.S. cyclones has been documented to cause localized intense precipitation rates and amounts. The life cycle and microphysics of the primary band within the comma head in the presence of mid-level frontogenesis and reduced stability has been documented, but there has been less attention investigating storms with multiple bands. The underlying hypothesis is that many of the quantitative precipitation forecast (QPF) errors associated with winter storms are the result of difficulties in models predicting these multi-bands given their smaller spatial scales, more convective characteristics, and their upscale growth to a single band.This team will integrate modeling and observational study to understand the spectrum of precipitation features within extratropical cyclones over the Northeast United States. Use ~20 years of radar data from the WSR-88Ds, several years of Terminal Doppler Weather Radar (TDWR) at the major airports, upper air soundings, observations from a vertically pointing radar, a disdrometer, and Multi-Angle Snowflake Camera (MASC) at Stony Brook, NY on Long Island, as well as high resolution gridded analyses and Weather Research and Forecasting (WRF) predictions to characterize banded precipitation and ice microphysics and to evaluate model output. The goal is to characterize band lifecycle and tracks of cells and bands around the cyclone and to quantify the importance to storm precipitation accumulation of multi-banded structures relative to other precipitation features. We will also identify what set of parameters are needed to realistically model multi-banded precipitation. Our work will address the parameterization of ice microphysics and mesoscale predictability of banded precipitation using an ensemble of historical runs and sensitivity studies.Intellectual Merit:Improvement in QPF during the cool season continues to lag our ability to predict the pressure and geopotential height fields within winter storms. This award will improve the understanding of the spectrum of precipitation features within the comma head of a mid-latitude cyclone by completing a comprehensive climatology of the genesis, growth, and decay of bands and cells over the Northeast U.S. region using an feature-based tracking algorithm. To date, there have also been no modeling studies using real cases focusing on the multi-band genesis and evolution around a mid-latitude cyclone, and the microphysical verification within all scales of bands has been limited. This work will provide an improved understanding of banded precipitation, which can be applied to other regions with bands within the comma head. Our ground-based microphysical work will evaluate and improve our new microphysics parameterization focusing on improving riming representation within models.Broader Impacts:Major winter storms in the northeast U.S. have wide ranging societal and economic impacts. The New York City Metropolitan Area is the home to nearly 20 million people and is a major transportation hub along the East coast. This area has been hit by several major storms in recent years (http://www.nyc.gov/html/oem/html/hazards/winter_history.shtml). The results from this project will help improve existing conceptual models used by forecasters to anticipate banded precipitation within the comma head as well as to improve the QPFs within mesoscale models. Dr. Colle and Dr. Yuter will each support one graduate student per year under this award. Several undergraduate research assistants will also be trained to do data processing and analysis. Their results will be presented by the students as posters at research symposia such as the ones held by NCSU and Stony Brook each spring and summer. Results will also be disseminated in conference presentations and journal articles. Additionally, Dr. Yuter plans to present a few general audience talks about snow and winter storms at local North Carolina science museum.