Radar Interferometric Studies of Jetstream Vertical Velocities and Precipitating Regions

摘要

The research project involved studies of the vertical circulation within frontal zones and near jet-streams using interferometric radar techniques. Application of interferometric techniques to determine the angle of arrival of the signal within the finite radar beam width has shown that nominal vertical beam measurements often have significant biases due to inclined aspect sensitive structures, especially in the vicinity of fronts and near jet streams. The interferometric technique makes it possible to apply corrections to the raw Doppler velocities which were then used to calculate the two-dimensional spectra of the velocity fluctuations as a function of the vertical wave number and frequency. The spectra that were calculated show two breaks. One is at the linear instability threshold determined by the wave breaking criterion. The other is at the boundary determined by the diffusive limit. In addition, the Scorer parameter which determines the vertical wave number cut-off for vertically- propagating orographic waves was found to be important in determining the character of the wave spectrum.