Nino海区SSTA的时频结构特征

根据1950～2003年Nino海区SSTA资料，采用小波变换方法分析了SST变化的多尺度结构及其强度变化。结果表明，Nino海区的SSTA序列表现为多层次相互嵌套的时频结构，存在着2～7a、8～20a和30a以上时间尺度的变化，经检验显著变化周期为2～7a，10a以上和1a以下的周期信号较弱。冷暖事件的能量主要集中在2～7a的尺度上，以准4a尺度的周期振荡最为显著。同一事件在不同海区的频率结构也不相同，1970年以后各尺度上冷暖事件的强度明显增大，有向低频发展的趋势。

Time-Frequency Structure of Sea Surface Temperature in Nino Regions

The time-frequency structure of sea surface temperature anomaly (SSTA) in the Nino regions was studied with wavelet transform techniques using SST data from 1950 to 2003 over the Nino regions. The results show that there were multi-scaled structures nested one another in SSTA with varied scales of 2-7, 8-20 and over 30 years. The power of the warm/cold events was concentrated on the 2-7 year scales with the quasi-four year fluctuation being the most remarkable. The power and frequency structure of the same event are different in different Nino regions. The intensity of oscillations is increasing at all scales after 1970 and shows a tendency towards low frequencies.