The Mechanisms for the Maintenance of Nocturnal Convective Systems

夜间对流系统的维持机制

• 批准号: 1237404
• 负责人: David Parsons
• 金额: $ 46.56万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1237404&HistoricalAwards=false
• 关键词: Mechanisms; Maintenance; Nocturnal; Convective; Systems

Supported investigators will focus on improved detection and understanding of mechanisms leading to formation and maintenance of nocturnal deep convection (i.e., thunderstorms developing well after the cessation of maximum daytime heating) under conditions that include a low-level jet, stable boundary-layer stratification and elevated instability as signified by the largest Convectively Available Potential Energy (CAPE) being located near the altitude of this low-level jet wind maximum. This work is motivated by recent idealized studies that point to the potential importance of undular bores and internal gravity waves in maintaining nocturnal convection over the Great Plains region, as well as recent case-studies of by these investigators showing that a positive feedback may potentially exist between nocturnal convection, bores and the pre-convective environment. This work will take advantage of the operational rawinsonde network, composite radar data analyses, and advanced wind profiler data to conduct an in-depth study of the impact of the nocturnal weather systems on convective instability, and in so doing will seek to generalize prior descriptions of mechanisms that may serve to trap the vertical propagation of wave energy. Additional measurements will be obtained using an FM-CW (frequency modulated continuous wave) radar, scanning Doppler lidar and serial soundings. Lidar (light detection and ranging) data will allow identification of situations in which bore-lifted air is serving to feed convective updrafts. Non-hydrostatic numerical simulations will be conducted to advance understanding of observational results.The Intellectual Merit of this effort will derive from characterization of the complex interplay among nocturnal convection, undular bores and gravity waves with emphasis on assessment of cases where positive feedbacks among these features may be responsible for convective maintenance. Broader Impacts will include graduate student involvement in data collection and analysis, as well as anticipated linkages to NSF-supported REU (Research Experiences for Undergraduates) programs at National Weather Center and through integration of results into courses offered at the School of Meteorology. Ultimately, desirable impacts are also expected through improved ability to predict nocturnal thunderstorm development over the Great Plains and anticipate associated impacts on surface hydrology, energy production and agriculture, as well as related increases in public safety in situations involving hazardous nocturnal weather. This effort is also well paired with NOAA's stated goal to assess effectiveness of increasing dependence of storm-scale short-term forecasts on numerical models, as in the "Warn-on-Forecast" initiative. Findings may also be applicable in other continental regions beyond the U.S. Great Plains that exhibit a nocturnal maximum in thunderstorm occurrence.

得到支助的调查人员将侧重于更好地探测和了解导致夜间深对流形成和维持的机制(即，在白天最大加热停止后雷暴很好地发展)，条件包括低空急流、稳定的边界层层结和不稳定加剧，这表明最大对流可用势能位于这一低层急流最大风速的高度附近。这项工作的动机是最近的理想化研究，这些研究指出波状钻孔和内部重力波在维持大平原地区夜间对流方面的潜在重要性，以及这些研究人员最近的案例研究表明，夜间对流、钻孔和对流前环境之间可能存在正反馈。这项工作将利用业务雷达探空仪网络、综合雷达数据分析和先进的风廓线数据，深入研究夜间天气系统对对流不稳定的影响，这样做将寻求推广先前对可能有助于捕获波能垂直传播的机制的描述。将使用FM-CW(调频连续波)雷达、扫描多普勒激光雷达和连续探测获得额外的测量结果。激光雷达(光探测和测距)数据将允许识别钻孔提升空气为对流上升气流提供支持的情况。将进行非静力数值模拟以促进对观测结果的理解。这项工作的智力价值将来自对夜间对流、波状钻孔和重力波之间复杂相互作用的描述，重点是评估这些特征之间的正反馈可能导致对流维持的情况。更广泛的影响将包括研究生参与数据收集和分析，以及预期与国家气象中心NSF支持的本科生研究经验(REU)项目的联系，以及通过将结果整合到气象学院提供的课程中。最终，通过提高对大平原夜间雷暴发展的预测能力，并预测对地表水文、能源生产和农业的相关影响，以及在涉及危险夜间天气的情况下公共安全的相关增加，预计也将产生令人满意的影响。这一努力也与NOAA声明的目标很好地结合在一起，即评估风暴规模短期预报对数值模式日益依赖的有效性，如“预报时警告”倡议。研究结果也可能适用于美国大平原以外的其他大陆地区，这些地区夜间雷暴发生的次数最多。