THE FREQUENCY CHARACTERISTICS OF WARM AND COLD EPISODES IN THE NIO REGIONS

On the basis of NOAA/CPC data of sea surface temperature anomaly in the Nio regions during Jan. 1950 – Dec. 2003, the wavelet power spectrum of SST were studied with significance and confidence testing at different scales in this paper. It shows that the SST are provided with multi-time scales structure nested one another, and vary on scales of 2 – 7 years, 8 – 20 years and >30 years. The most significant variation of the warm and cold episodes is in the 4-year band of period. The power, frequency structure and confidence of the same episode are different in different Nio regions. The intensity of oscillations is increasing at low frequency bands and decreasing at high frequency bands from east to west in the Ni?o regions, especially after 1970.