Orographic Influences on Lake-Effect Storms

安大略省冬季（OW）湖泊效应系统（LeS）实地活动将涉及多个大学和非营利组织团体，他们希望更好地了解控制美国五大湖地区及周边地区大雪的时间和位置以及相关云结构的机制。OWLeS期间将部署的观测设备包括怀俄明大学的King Air、CSWR多普勒轮式移动雷达、多个探空系统、米勒斯维尔大学剖面系统、UAH移动综合剖面系统以及各种其他地面原位仪器。这个特别的研究小组的活动重点是LeS和更高地形的影响的交集，例如以纽约州北部的托格山高原地区为代表。他们将利用气候学分析、实地研究、实际数据数值模拟和理想大涡模拟来解决与LeS相关的两个首要问题：1)在湖效应风暴期间，环境条件、云过程、湖泊形状和大小、地形尺度和几何形状之间的相互作用如何影响地形降水增强？2)在什么条件下地形改变了低海拔区域的地形形态以及周边低地地区降水的产生、分布和强度？研究的主要区域将是大盐湖周围地区和安大略湖下风的托格山高原。该小组计划为OWLeS的实地工作提供两个雪观测站和一个可部署的降雨探测系统。本文的理论价值集中在以下三个主要假设的评价上：1)相对于下游障壁波峰的封顶反转或稳定层的高度调节地形降水增强和低地与山地的降水比；(2)在无阻塞湖效应事件中，湖效应系统的冰粒生长和沉降以及边界层湍流是地形降水的重要贡献者；③大的湖地温差和相关的陆风辐合产生湖泊主导事件，而地形主导事件发生在湖地温差较弱的时期。该项目的更广泛影响将包括本科生参与数据收集、教育和培训两名研究生（其中一名来自代表性不足的大气科学群体）以及各种外联活动。这项研究有可能有助于改善湖泊效应暴雪事件的预测，从而支持社会和经济效益。

The Ontario Winter (OW) Lake-effect Systems (LeS) field campaign will involve multiple university and non-profit organizational groups who week to better understand mechanisms controlling the timing and location of heavy snowfall and associated cloud structures over and around the U.S. Great Lakes region. Observational assets to be deployed during OWLeS include the University of Wyoming King Air, the CSWR Doppler on Wheels mobile radars, multiple sounding systems, the Millersville University Profiling System, the UAH Mobile Integrated Profiling System, and a variety of other surface in-situ instruments. The focus of this particular research team's activities is on the intersection of LeS and influences of higher terrain, e.g. as represented by the Tug Hill Plateau region of upstate New York. They will make use of climatological analysis, field research, real-data numerical modeling and idealized large-eddy simulations to address two overarching questions related to LeS: 1) How does the interplay between environmental conditions, cloud processes, lake shape and size, and terrain scale and geometry affect orographic precipitation enhancement during lake-effect storms?; and 2) Under what conditions does orography modify the morphology of LeS and the generation, distribution, and intensity of precipitation over surrounding lowland areas?The main regions of study will be areas around the Great Salt Lake and the Tug Hill Plateau downwind of Lake Ontario. This team plans to contribute two snow observation stations and a deployable rawinsounding system to OWLeS field effort. The intellectual merit of this effort is centered on evaluation of the following three main hypotheses: 1) The height of the capping inversion or stable layer relative to the downstream barrier crest regulates orographic precipitation enhancement and the lowland to mountain precipitation ratio; 2) Ice particle growth and fallout from the lake-effect system and boundary layer turbulence are important contributors to orographic precipitation in unblocked lake-effect events; and 3) Large lake-land temperature contrasts and associated land-breeze convergence yield lake-dominated events, whereas terrain-dominated events occur during periods with weaker lake-land temperature contrasts. Broader impacts of the project will include the participation of undergraduate students in data collection, education and training of two graduate students, one of which is drawn from an underrepresented group in atmospheric sciences, and various outreach activities. This research has the potential to contribute to improved prediction of lake-effect heavy snow storm events, which would in turn support both societal and economic benefits.