Application of a Refined Emergency Code System SPEEDI to Atmospheric Field Experiments Conducted over a Complex Terrain

Abstract

An environmental emergency code system SPEEDI consisting of a mass consistent wind field model and a lagrangian particle dispersion model is taken up for validation study using the benchmark data obtained from a series of field experiments conducted over a complex terrain. During the experiments extensive data on meteorological parameters were collected and in addition SF6 tracer gas was released and sampled by thickly distributed samplers. An isolated hill placed on an otherwise flat terrain provides a special geometrical situation so that the data can be used for testing the model simulation of stream line deflections past an obstacle. An objective basis for relating the ratio of Gauss precision moduli which controls the horizontal to vertical adjustment of the wind components has been introduced in the wind field model and the results show great improvement particularly when the parameter is allowed to vary with height. Results of the tracer release experiments confirm the improvements. The modified wi...