9629567 Young Much of the energy that drives atmospheric circulations is obtained through exchanges of heat, moisture, and momentum with the surface. Lake-effect events, where cold air masses are rapidly modified over the Great Lakes, are excellent natural laboratories for studying these exchanges. The Lake- Induced Convection Experiment (Lake-ICE) is a multiple- Principal Investigator project which seeks to use this natural laboratory to determine how boundary layer growth processes are controlled by mesoscale boundary layer convective structures and how the modified boundary layer effects the production of precipitation and the larger scale meteorological conditions. Because of strongly nonlinear multi-scale interactions, the study of lake-induced phenomena requires a highly collaborative team effort taking advantage of the skills of multiple investigators and the capabilities of a range of instruments and platforms. Within the broader framework of Lake-ICE the research to be performed under this award will focus on two scientific objectives: 1. To determine the nature, causes, and consequences of the two-way interaction between individual km-scale convective elements (i.e. three-dimensional thermal plumes) and the two- dimensional mesoscale lake-effect cloud bands in which they are embedded. 2. To ascertain the degree to which these interactions lead to a mesoscale modulation (i.e. cross-roll variation) in the rate at which air is entrained across the temperature inversion that caps the lake-induced convective boundary layer. ***