Convective Rolls and Cells in Lake-effect Snowstorms: Structures, Mechanisms and Effects

为了充分确定天气尺度环流和地面特征之间的联系，必须了解对流边界层内的中尺度流动。观测证据表明，理论标准在预测边界层中主要的中尺度对流组织时往往是不成功的。特别是，当预测细胞对流时，经常观察到被称为卷的边界层流动结构。本研究旨在采用数值和观测相结合的方法：(1)确定控制湖效应暴雪边界层滚动发展的因素；(2)确定对流的中尺度组织如何影响质量倾覆率、降水率和边界层深度。第一个目标将通过仔细记录密歇根湖东岸附近中尺度对流的三维结构，以及它如何随逆风大气条件和边界层风、温度和水分（冰、液体和蒸汽）剖面的演变而变化来实现。数值模拟将在观测条件范围内进行，以提供更完整的数据集，以确定风切变、潜热释放和其他因素对边界层对流组织的影响。中尺度对流组织对质量倾覆率、降水率和边界层深度的影响将通过仔细记录这些特征在顺风岸附近的变化来完成，这些特征在观测和快速变化的中尺度对流结构的模拟中都是如此。这项工作是基于芝加哥大学湖雪项目期间的观察结果。这项工作的数值方面将与俄克拉荷马大学风暴分析和预测中心开发的高级区域预测系统模型一起进行。这项研究将由伊利诺斯州水资源调查和南达科他州矿业与技术学院合作进行。＊＊＊

9510098 Kristovich Mesoscale flows within convective boundary layers must be understood in order to fully determine the link between synoptic-scale circulations and surface characteristics. Observational evidence suggests that theoretical criteria are often unsuccessful in predicting the predominant mesoscale convective organization in the boundary layer. In particular, boundary layer flow structure knows as rolls are often observed when cellular convection is predicted. The proposed study seeks to employ both numerical and observational techniques to: (1) determine factors which control the development of boundary layer rolls in lake-effect snowstorms; and (2) determine how the mesoscale organization of convection influences mass overturning rates, precipitation rates, and boundary layer depth. The first goal will be accomplished by careful documentation of the three-dimensional structure of mesoscale convection near the eastern shore of Lake Michigan and how it varies with upwind atmospheric conditions and evolution of boundary layer winds, temperature, and moisture (ice, liquid, and vapor) profiles across the lake. Numerical simulations will be carried out over the range of observed conditions to give a more complete data set for determining the influence of wind shear, latent heat release, and other factors, on the organization of boundary layer convection. The influence of mesoscale convective organizations on mass overturning rates, precipitation rates, and boundary layer depth will be accomplished by carefully documenting how these features change near the downwind shore in both observations and simulations of rapidly changing mesoscale convective structure. This work is based on observations taken during the University of Chicago Lake Snow Project. Numerical aspects of this work will be carried out with the Advanced Regional Prediction System model developed at the Center for Analysis and Prediction of Storms at the University of Oklahoma . This research will be a collaborative effort between the Illinois State Water Survey and the South Dakota School of Mines and Technology. ***