Orographic Influences on Lake-Effect Storms

安大略省冬季(OW)湖泊效应系统(LES)实地活动将有多所大学和非营利性组织参与，他们将参加为期一周的活动，以更好地了解美国五大湖区上空和周围大雪的时间和位置以及相关云结构的控制机制。猫头鹰期间将部署的观测资产包括怀俄明州国王航空大学、CSWR车轮上的多普勒移动雷达、多探测系统、米尔斯维尔大学剖面系统、UAH移动综合剖面系统和各种其他地面原位仪器。这一特定研究小组的活动重点是LES和更高地形的影响的交汇处，例如纽约州北部的塔格山高原地区。他们将利用气候学分析、实地研究、真实数据数值模拟和理想化大涡模拟来解决与LES相关的两个主要问题：1)环境条件、云过程、湖泊形状和大小、地形规模和几何形状之间的相互作用如何影响湖效风暴期间地形降水的增加？2)在什么条件下，地形改变了LES的形态和周围低地地区降水的产生、分布和强度？主要研究区域将是大盐湖周围地区和安大略湖顺风向的拖格山高原。这个团队计划为猫头鹰的野外工作贡献两个雪地观测站和一个可部署的探测系统。这一努力的学术价值集中在对以下三个主要假设的评估上：1)封顶逆温或稳定层相对于下游屏障顶峰的高度调节了地形降水的增加和低地与山区的降水比；2)冰粒子的增长和来自湖泊效应系统和边界层湍流的降雨量是畅通的湖泊效应事件中地形降水的重要贡献因素；以及3)大的湖泊-陆地温度对比和相关的陆风辐合产生了以湖泊为主的事件，而地形主导的事件发生在湖泊-陆地温度对比较弱的时期。该项目的更广泛影响将包括本科生参与数据收集、两名研究生的教育和培训，其中一名研究生来自大气科学中代表性不足的群体，以及各种外联活动。这项研究有可能有助于改进对湖泊影响的大雪事件的预测，这反过来将支持社会效益和经济效益。

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.