Collaborative Research: Investigations of Non-Classic Lake-Effect Boundary Layer Processes

研究和业务天气观测系统以及数值模拟技术的进步，使人们对湖泊效应暴风雪的发展和演变所涉及的物理过程的理解逐步提高。特别是最近在湖泊诱导对流实验（lake- ice）和中尺度数值模式中取得的观测结果，已被用来更好地理解主要由秋冬月份的湖泊表面热量和水分通量发展起来的孤立的“经典”湖泊效应系统。对经典湖泊效应系统中微尺度和中尺度过程之间相互作用的科学认识得到加强，现在可以应用于更复杂的、也许更常见和更强烈的非经典湖泊效应风暴。该合作研究项目将以过去的研究成果为基础，利用新的观测和数值模式，对天气系统和中尺度湖泊效应系统之间复杂的相互作用，以及控制中尺度湖泊效应对流带的相干性和结构的因素，形成物理上一致的认识。特别是，主要研究人员将分析从雷达、飞机、卫星和地面仪器获得的数据，并进行详细的中尺度模型模拟，以研究非经典湖泊效应情况下尚未解决的问题。具体研究目标有四个：1)确定有大尺度降水和无大尺度降水时湖效应边界层云微物理结构和热力学的差异；2)确定暖湖对移动中尺度降水系统（如与天气锋相关的）的中尺度动力学和结构的影响；3)确定逆风湖泊对流边界层和中尺度环流对顺风湖泊湖效应发展的影响过程；4)确定湖效应雪带中尺度结构发展的动力机制以及垂直风切变对雪带结构相干性的影响。本研究的成功完成将有助于改善强湖效应暴雪的预报。

Advances in research and operational weather observation systems and numerical modeling techniques have led to progressive improvements in understanding of physical processes involved in the development and evolution of lake-effect snow storms. In particular recent observations taken during the Lake-Induced Convection Experiment (Lake-ICE) and mesoscale numerical models have been utilized to better understand isolated "classic" lake-effect systems that develop primarily from lake surface heat and moisture fluxes in fall and winter months. The enhanced scientific understanding of interactions between microscale and mesoscale processes in classic lake-effect systems can now be applied to more complex, and perhaps more common and intense, non-classic lake-effect storms.This collaborative research project will build on past research results and use new observations and numerical models to develop a physically-consistent understanding of complex interactions of synoptic systems and mesoscale lake-effect systems and factors controlling the coherence of, and structure along, mesoscale lake-effect convective bands. In particular the Principal Investigators will analyze data obtained from radars, aircraft, satellites and surface instrumentation and perform detailed mesoscale model simulations to study unresolved issues for non-classic lake-effect situations. Four specific research objectives are to: 1) Determine differences in the cloud microphysical structure and thermodynamics of lake-effect boundary layers that occur with and without large-scale precipitation aloft; 2) Determine the effects of a warm lake on the mesoscale dynamics and structure of moving mesoscale precipitation systems (such as associated with synoptic fronts); 3) Determine the processes by which the convective boundary layer and mesoscale circulations from an upwind lake influence lake-effect development over a downwind lake; 4) Determine the dynamic mechanisms leading to the development of mesoscale structures along lake-effect snow bands and the influence of vertical wind shear on band structural coherence. Successful completion of this research could help improve the forecast of intense lake-effect snowstorms.