Improving Understanding of Convection Initiation in Nocturnal Environments During PECAN (Plains Elevated Convection at Night) Using High-Resolution Ensemble Data Assimilation

使用高分辨率集合数据同化提高对 PECAN（夜间平原高对流）期间夜间环境中对流启动的理解

• 批准号: 1541624
• 负责人: Katja Friedrich
• 金额: $ 59.21万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-12-01 至 2020-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1541624&HistoricalAwards=false
• 关键词: Improving; Understanding; Convection; Initiation; Nocturnal

Nocturnal thunderstorms in the central United States provide rainfall for productive agricultural regions but also can pose hazards to lives and property through flooding and severe winds. In 2015, NSF funded a large group of scientists to collect data on these nighttime thunderstorms. This award will make use of that data by conducting very small scale numerical modeling studies to determine what initially triggers the thunderstorms, a process known as convective initiation. The research has the potential to improve understanding and modeling of these events, giving forecasters more information about when and where thunderstorms may happen. The award would also contribute to human resource development by funding an early-career researcher, providing an opportunity for an undergraduate student to participate in a research project, and allowing the researcher to develop a seminar course based on the field campaign.The Plains Elevated Convection at Night (known colloquially as PECAN) field campaign was conducted in the Great Plains region in June and July of 2015. The campaign included numerous observational platforms, such as mobile radars, aircraft, vertical profilers and surface instrumentation. In this project the researcher intends to assimilate data from the campaign into an ensemble with nested mesoscale and convection-resolving grids. The primary focus of the research is to accurately reproduce the evolution of the nocturnal mesoscale environment in which convective initiation occurs and to determine which specific small- and large-scale processes result in parcels lifted to their level of free convection. The ensemble data assimilation experiments will employ the WRF-ARW and the Data Assimilation Research Testbed (DART) ensemble analysis software configured as an Ensemble Adjustment Kalman Filter. Fifty ensemble members will be used and the researcher plans to employ a triple nested model grid strategy with the finest grid spacing of 0.4 to 0.6km. In addition to the work on identifying processes triggering nocturnal convection, the researcher will also conduct forecast sensitivity experiments.

美国中部的夜间雷暴为生产性农业地区提供降雨，但也可能通过洪水和强风对生命和财产造成危害。 2015年，美国国家科学基金会资助了一大批科学家收集这些夜间雷暴的数据。 该奖项将利用这些数据进行非常小规模的数值模型研究，以确定最初引发雷暴的原因，这一过程被称为对流引发。 这项研究有可能提高对这些事件的理解和建模，为预报员提供有关雷暴何时何地可能发生的更多信息。 该奖项还将通过资助一名早期职业研究人员、为本科生提供参与研究项目的机会以及允许研究人员根据实地活动开发研讨会课程来促进人力资源开发。 2015 年 6 月和 7 月，在大平原地区进行了夜间（俗称 PECAN）野外活动。该活动包括许多观测平台，如移动雷达、飞机、垂直剖面仪和地面仪器。 在这个项目中，研究人员打算将活动中的数据吸收到具有嵌套中尺度和对流解析网格的集合中。 该研究的主要重点是准确再现对流引发发生的夜间中尺度环境的演变，并确定哪些特定的小尺度和大尺度过程导致地块提升到自由对流水平。 集合数据同化实验将采用 WRF-ARW 和配置为集合调整卡尔曼滤波器的数据同化研究测试台 (DART) 集合分析软件。 将使用 50 名集成成员，研究人员计划采用三重嵌套模型网格策略，最细网格间距为 0.4 至 0.6 公里。 除了识别引发夜间对流的过程外，研究人员还将进行预测灵敏度实验。