Hidden Periodicities for Time Series Data of Hourly Air Temperature around East Asia Region

Correlations between time series data of hourly air temperature from 1991 to 2010 observed at Kobe station and Niigata station are discussed. For time series data of hourly air temperature in 1996, 2000, 2009, and 2010, power spectra with periodic peaks are calculated by using Fourier transform, respectively. A first peak of power spectra is determined and time intervals between nearest neighbor peaks are evaluated. As a result, hidden periodicities are observed. In addition, the features of power spectra for the ratio of cloud covers and space packing exponents by image analysis and time series analysis for MTSAT-2 images covering East Asia region of channels IR1 in 2009 and 2010 are described and similarities between the hidden periodicities for time series data of hourly air temperature are suggested