Details

Autor(en) / Beteiligte

• Takahashi, K.
• Collaborators

Titel

Studies on the Seasonal Weather Forecasting (II): Periodicities in Meteorological Phenomena

Ist Teil von

• Papers in Meteorology and Geophysics, 1952/08/31, Vol.3(1), pp.26-40

Ort / Verlag

Japan Meteorological Agency / Meteorological Research Institute

Erscheinungsjahr

1952

Link zum Volltext

Quelle

EZB-FREE-00999 freely available EZB journals

Beschreibungen/Notizen

• Predominating periods of daily pressures at several stations in Japan were investigated by harmonic analysis. W e found 5-,12-13-day and probably 4- and 10-day periods predominated throughout the year. Analysing 5-day mean values of pressure and temperature deviations from the normal at some stations over Asia and the North Pacific, we found 25-,35-,4 5-, and 65-day periods predominated. The latter long periods coincide with the values which were analysed formerly by s o-called periodogram analysis.5- and 9-month periods were als o found to predominate. Assuming such a long period,5-day mean pressure at the stations over the Northern Hemisphere was analysed by harmonic analysis, and we found that they were expressed approximately by a regular standing oscillation of pressure over the earth. Next,8-day period of pressure ove r the Northern Hemisphere was analysed by similar methods, and such an oscillation was suggested to be an internal wave of atmosphere. Among many short periods,4-day period at 500 mb level over the Northern Hemisphere was investigated in detail.8or 9 planetary waves round the Northern Hemisphere seem to be the origin of the 4-day period. Heights of 500 nib level along latitude 50° N in winter were analysed into elementary sinusoidal waves by harmonic analysis and two, kinds of waves, one a stationary and the other a propagating wave, were found. It was found that long waves propagate' towards the west and short waves towards the east. Thus, modes of the oscillation of long periods and short periods are quite different. Some trials of long range forecasting we r e made, assuming such periodicities. Analysing the pressure variations of several stations to the elementary oscillation and extrapolating such elementary oscillation to the future and adding them, the forecasted values of pressure are obtained.