A Hypothetical Explanation of Unusual Barometric Oscillations: A Case Study

Widespread unusual barometric oscillations over the North Island of New Zealand on 2nd to 3rd of April 1975 are investigated with the view of finding an explanation of their cause. The synoptic situation on the days concerned is explored in detail. It is deduced that by comparing actual speeds of dissemination with the theoretical speed, and the magnitude of the oscillations as deduced from upper air data with surface pressure variations, the oscillations can be explained as being "shallow water" gravity-buoyancy waves. The discrepancy between the two speeds is justified by explaining the shortcomings of the observational data.