A Numerical Study of Atmospheric Density Current Motion Including the Effects of Condensation

Abstract

A new form of the density current speed equation is presented which uses the surface pressure rise to predict the speed of the current front. This allows the speed prediction to be made with only surface measured quantities. This form of the equation is tested on gust front observations and numerical density current simulations and found to give good results. A simple, moist numerical model is used to simulate dry density currents and moist currents which produce an arc/rop cloud. The numerical results provide information on the lifting associated with density current passage and the forced updraft velocities at the front, and also show that use of the pressure form of the density current speed equation is especially important when condensation is occurring above the density current.