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

改进对温带气旋内降水的预报需要继续整合观测和模型，以了解与降水带有关的演变和过程。美国东北气旋逗号头部分的中尺度条带已被记录为导致局部强烈降雨率和降雨量的原因。在中层锋生和稳定度降低的情况下，逗号头部主要频带的生命周期和微观物理已被记录在案，但对具有多个频带的风暴的研究较少。基本的假设是，许多与冬季风暴有关的定量降水预报(QPF)误差是由于这些多波段的空间尺度较小、对流特征较多以及它们的高尺度增长到单一波段而难以预测的结果。该团队将结合模拟和观测研究来了解美国东北部温带气旋内的降水特征频谱。使用来自WSR-88DS的大约20年的雷达数据、主要机场数年的终端多普勒天气雷达(TDWR)、高空探测、垂直指向雷达、碟形仪和位于纽约长岛石溪的多角度雪花相机(MASC)的观测，以及高分辨率网格分析和天气研究和预报(WRF)预测，以描述带状降水和冰的微物理特征并评估模式的输出。目标是确定气旋周围的气旋带的生命周期和轨迹，并量化多带结构相对于其他降水特征对风暴降水积累的重要性。我们还将确定需要哪组参数来真实地模拟多带降水。我们的工作将使用历史运行和敏感性研究的集合来解决冰微物理的参数化和带状降水的中尺度可预报性。智慧的优点：在寒冷的季节QPF的改善仍然落后于我们预测冬季风暴中的气压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对美国东北部地区带状和单体的发生、生长和衰变的全面气候学研究，从而提高对中纬度气旋逗号头部降水特征的理解。到目前为止，还没有关于中纬度气旋周围多个气旋带发生和演化的真实案例的模拟研究，所有尺度上的微物理验证都是有限的。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部内有带状降水的其他地区。我们的地面微物理工作将评估和改进我们新的微物理参数化，重点是改善模型中的边缘表示。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。纽约市大都市区是近2000万人的家园，也是东海岸的主要交通枢纽。这一地区近年来遭受了几次大风暴的袭击。该项目的结果将有助于改进预报员用来预测逗号头部内的带状降水的现有概念模式，以及改善中尺度模式内的QPF。根据这一奖项，科尔博士和尤特博士每人每年将资助一名研究生。几名本科生研究助理也将接受培训，进行数据处理和分析。他们的成果将由学生以海报的形式在研究研讨会上展示，比如NCSU和Stony Brook每年春天和夏天举办的研讨会。结果还将在会议报告和期刊文章中传播。此外，尤特尔博士还计划在北卡罗来纳州当地的科学博物馆为观众做几场关于降雪和冬季风暴的演讲。

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.