Most winter time severe weather in temperate latitudes is associated with cold fronts. These transition zones between warm air to the south and cold air to the north represent the focus of weather forecasts. The models used by most weather services often produce accurate forecasts of these weather systems, but errors, when they occur, may in part be associated with motions that occur on scales that are less than the resolution, in space and time, of the numerical models. One way to alleviate errors in numerical forecasting models is to carry out research programs to observe small-scale, high-frequency motions and to use this information to introduce sub-grid scale effects by parameterizing their effects in a physically realistic manner. The proposed investigation makes use of observations obtained from two observational programs that have been supported, in part, by the National Science Foundation: the Stormscale Operational Research Meteorology-Fronts Experiment Systems Test (STORM-FEST, 1992) and MICROFRONTS, 1995. Observations on the scale of fronts from tens of kilometers down to millimeter scale were accumulated by means of both sonic and hot-wire anemometers. A principal objective is to document the dissipation of turbulent kinetic energy near frontal surfaces in the Earth's boundary layer. The data from MICROFRONTS serves this purpose, and these data will be used to verify the accuracy of various theories associated with dissipative processes. Knowledge of turbulent dissipative processes, in both space and time, is necessary to provide more realistic parameterizations of boundary layer dissipation for use in forecast and research models. A second objective is associated with the improvement of a classical theoretical model that provides a physical explanation of the frontal contraction process, so-called frontogenesis. This model neglects certain features that have been observed in a frontogenesis event that occurred during STORM-FEST: inertial oscillations with periods of about 17 hours. The effect of these oscillations on frontogenesis and the accompanying motions will be included in a theoretical development. The solutions do not take account of dissipative processes that become important when the front is within the boundary layer. The blending of dissipative processes, as determined by the former investigation, into theoretical models that either handle such effects crudely or not at all, is a long-range goal of this research.***
