Turbulent Dissipation in Frontal Zones from Hot-Wire Measurements in the MICROFRONTS Experiment

摘要

Measurements of turbulent dissipation of kinetic energy have been taken of synoptic and small scale density frontal passages during the MICROFRONTS (MARCH 1999, Kansas) field program. It is revealed that there is a significant increase of turbulent kinetic energy during each-passage of the frontal transition zone. Data analyses suggest a linear relationship between the frontal width and the enhanced kinetic energy dissipation rate. A theoretical development supports this observational result. The conclusion is, however, tentative, because the data are limited and some physical processes have not been taken into account. The source of turbulence associated with a shallow density front and trailing current is also analyzed. The characteristics of dissipation in this small scale event, and the heat budget associated with the front and current are determined. Other analyses carried out as part of the front-boundary layer focus of this investigation, include the investigation of the turbulence and heat budget characteristics of the lowest 10 meters of the atmosphere as a function of static stability, and the characteristics of frontogenesis in the presence of inertial oscillations. The various results obtained are all related to the development of parameterization schemes that are required by weather prediction models.