Abstract
During the period from June 16 to 23, 1969, oscillations in height, temperature and wind with a period of about 2.5 days were detected in the upper troposphere over the Japan Islands. Detailed analysis shows that these periodic variations were associated with a weak disturbance with a wavelength of about 4, 000km around the jet stream in the Baiu frontal zone.
Structure and energetics of the disturbance will be described based on the periodic variations which were picked up by fitting a sinusoidal curve to 6-hourly observed values. Energetic consideration indicates that the disturbance is a baroclinic wave. The kinetic energy of the disturbance is produced from potential energy below the jet core and from kinetic energy of the mean flow just north of the jet axis. It is, however, inferred that the essential energy source is potential energy.
