The Mechanisms for the Maintenance of Nocturnal Convective Systems

支持的研究人员将专注于改进对导致夜间深层对流形成和维持机制的探测和理解（即，雷暴在白天最大加热停止后发展良好），这些条件包括低空急流、稳定的边界层分层和不稳定性升高，这表明最大对流有效势能（CAPE）位于低空急流最大风高度附近。这项工作的动机是最近的理想化研究，这些研究指出起伏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、孔和对流前环境之间可能存在正反馈。这项工作将利用可操作的雷达探空网络、复合雷达数据分析和先进的风廓线数据，对夜间天气系统对对流不稳定性的影响进行深入研究，并在此过程中寻求对可能有助于捕获波浪能量垂直传播的机制的先前描述进行概括。额外的测量将使用FM-CW（调频连续波）雷达、扫描多普勒激光雷达和串行测深。激光雷达（光探测和测距）数据将允许识别钻孔抬升空气为对流上升气流提供动力的情况。将进行非流体静力数值模拟，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负责对流维持的情况。更广泛的影响将包括研究生参与数据收集和分析，以及与国家气象中心nsf支持的REU（本科生研究经验）项目的预期联系，并通过将结果整合到气象学院提供的课程中。最终，通过提高预测大平原夜间雷暴发展的能力，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，预计也会产生理想的影响。这一努力也很好地配合了NOAA的既定目标，即评估越来越依赖于数值模型的风暴规模短期预报的有效性，如“预报预警”倡议。研究结果也适用于美国大平原以外的其他大陆地区，这些地区在雷暴发生时表现出夜间最大值。

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.