Evolutions of the Spectra of Historical Flood/Drought Fluctuations

Spectral analysis has often been adopted in the research field of climatic changes.Many authors defined significant periods from the spectra, by which they might fore-cast future climates. Unfortunately, important differences among the results havelong been neglected because the previous authors always stressed only the similaritiesbetween their results and the others. No serious discussion was made fromthe viewpoint of periodic climatic changes. The difficulty in getting deep insight into