Continued Lidar and Numerical Investigation of the Internal Boundary Layer Observed During Lake-Ice

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Much of the energy that drives atmospheric circulations is obtained through exchanges of heat, moisture, and momentum with the surface. To study these processes over the Great Lakes, a project known as the Lake-Induced Convection Experiment (Lake-ICE) was held over Lake Michigan in the winter of 1997/98. The University of Wisconsin Volume Imaging Lidar acquired a unique data set during the Lake-ICE field project. These data will be used to validate the performance of a microscale model of the atmospheric boundary layer in a continuation of the research begun during Lake-ICE. The University of Wisconsin Nonhydrostatic Modeling System will be used for the model simulations. Model results will be compared directly to the structural features of the boundary layer observed by the VIL using verification techniques developed under prior NSF support.This work is an effort to simulate both the evolution of the large-scale flow and the microscale flow structures, forced by local topographical and land use features. There is a great deal of interest by the public, private and military sectors in such forecast products. Currently little is known about the validity of model simulations of specific microscale structures. Moreover, understanding of the flow dynamics on this scale has been limited to mostly studies that focus on statistical properties of steady flow, rather than the direct simulation of specific evolving structures, which may be tied to specific topographic features such as hills, buildings, and lakeshore geometry. This is a unique effort to validate model simulations of microscale features against very high-resolution observations.Project goals are to (1) assess the ability of a microscale model to simulate the local response to predicted large scale flow evolution and (2) increase understanding of the forcings and dynamics leading to the observed coherent structures. The Principal Investigator will concentrate on two observed phenomena: (a) the genesis of Lake-ICE rolls and (b) the coastal front observed on 21 December.If successful, this research will advance knowledge of atmospheric boundary layer systems and develop analysis methodologies useful in studying such systems. This potentially could lead to better understanding and forecasting of such phenomena as the transport and diffusion of pollutants through complex terrain.