A study of winds and waves

Abstract

The project involved an observational program to study the lee waves produced over Canterbury due to the Southern Alps over the year 1970 using superpressure balloons and radar-wind/radiosonde balloons. The characteristics and performance of balloons (tetroons) and balloon systems were studied in detail. The data from the balloons was used to obtain a wave classification which may be used to predict the scale of wave motion from the radar-wind profile. It was also compared with solutions of two-, three- and exponential layer models to evaluate their applicability in predicting the wave motion. It was found that they gave a good correlation with observations when the atmosphere was approximated by layers but generally the airflow profiles were more complex and the layer theories at best predicted the scale of the wavelengths observed. The amplitudes of the waves were found to be mainly dependent on the resonance between the forcing periodicities of the mountains and the natural oscillations of the airflow.