Mechanisms for Severe Wind Production in Nocturnal and Transitioning Convection

GSTDTAP

项目编号	1442054
	Mechanisms for Severe Wind Production in Nocturnal and Transitioning Convection
	Karen Kosiba
主持机构	The Center for Severe Weather Research
项目开始年	2015
	2015
项目结束日期	2017-12-31
资助机构	US-NSF
项目类别	Continuing grant
项目经费	143295(USD)
国家	美国
语种	英语
英文摘要	The transition from surface-based to elevated convection and the subsequent organization and evolution of mesoscale convective systems (MCSs) as the nocturnal stable boundary layer (NSBL) develops is not well understood, complicating the forecastability of severe winds. During the transition from discrete cells to an MCS, severe surface winds may be generated but the processes responsible for the onset, intensification, and cessation of these winds are uncertain. Likely the hydrometeor type, distribution, and evolution within these MCSs, as well as the evolving properties of the NSBL, environmental shear and other factors play important roles in the initiation and maintenance of intense, surface-reaching downdrafts. The research will investigate how intense-wind-causing downdrafts reach the surface in the presence of a NSBL through characterization of the MCS and transitioning-to-MCS convective system kinematics, thermodynamics and microphysics, and how these are influenced by the local environment. This study uses data from the Plains Elevated Convection at Night (PECAN) project, planned for 2015, in addition to already collected but less complete data sets from the field programs. PECAN kinematic, thermodynamic and microphysical data obtained from a large and diverse array of observing data will enable the study of initiation/transition, evolution, internal kinematics and microphysics of severe-wind-producing MCSs. Multiple-Doppler analysis will be used to quantify the 3D winds through the depth of the MCS. Internal microphysical processes will be inferred from the radar reflectivity and dual-polarization fields and surface disdrometer data. Sounding systems and wind profilers will be used to diagnose atmospheric stability, depth of the NSBL, vertical wind structure and the location of the nocturnal low-level jet (LLJ). Mobile mesonet and stationary weather stations including Pods and PISAs, will be used to quantify the strength and horizontal extent of the surface cold pool, and quantify severe winds at the surface. Intellectual Merit: The multi-platform integrated observational study will result in a better understanding of the microphysical, thermodynamic and kinematic processes underlying nocturnal MCS evolution, transition from daytime to nocturnal/MCS organization, and how these are influenced by the NSBL during severe wind events. The research will result in a better understanding of the factors leading to the occurrence (or non-occurrence) of severe nocturnal winds. This research will also provide analyses fundamental to understanding whether severe-wind producing MCSs are elevated, surfaced-based, or hybrid systems, the microphysical composition of these systems, and the kinematics of these systems before, during, and after the occurrence of severe surface winds, and how they are affected by the local environment. Broader Impacts: Analyses, results, and improved scientific understanding from the research will be made available to the modeling and forecasting communities. Improvements to numerical models and hence the forecasting of the occurrence, severity and timing of nocturnal severe-wind producing MCSs will benefit from these fine-scale observational analyses through comparison with model output and predictions. Better understanding, leading to improved forecasts will aid in mitigating the impact of these severe-wind producing events. Education of students through the development of a PECAN-specific university course focusing on radar and mesoscale observations, participation in the field phase of PECAN, and subsequent analysis efforts will help train the next generation of scientists.
来源学科分类	Geosciences - Atmospheric and Geospace Sciences
文献类型	项目
条目标识符	http://119.78.100.173/C666/handle/2XK7JSWQ/67455
专题	环境与发展全球科技态势
推荐引用方式 GB/T 7714	Karen Kosiba.Mechanisms for Severe Wind Production in Nocturnal and Transitioning Convection.2015.