Interdecadal Variations of ENSO Signals and Annual Cycles Revealed by Wavelet Analysis
Interdecadal Variations of ENSO Signals and Annual Cycles Revealed by Wavelet Analysis
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小波分析揭示的ENSO信号和年周期的年代际变化
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
Shinji Umatani
中科院分区：
文献类型：
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作者：
Takashi Setoh;S. Imawaki;A. Ostrovskii;Shinji Umatani
利用小波分析、经验正交函数分析和奇异值分解分析方法，研究了1950-1997年赤道太平洋海温和纬向风的ENSO信号和年周期的年代际变化。厄尔尼诺/南方涛动的典型时间尺度估计在1970年代后期之前约为40个月，之后为48-52个月;时间尺度增加了约10个月。20世纪70年代以来，ENSO信号的空间分布也发生了变化，在此之前，ENSO信号的强区主要分布在赤道外，而在此之后，ENSO信号的强区主要分布在赤道附近。最强信号中心由赤道太平洋中东部向南美洲沿岸移动。赤道附近的SST波动与纬向风的波动有关，纬向风的空间分布也在当时显著东移。在赤道东太平洋，海温年周期的振幅在厄尔尼诺年较弱，在拉尼娜年较强。然而，在1980年代和1990年代，这种关系并不清楚。
Interdecadal variations of El Niño/Southern Oscillation (ENSO) signals and annual cycles appearing in the sea surface temperature (SST) and zonal wind in the equatorial Pacific during 1950–1997 are studied by wavelet, empirical orthogonal function (EOF) and singular value decomposition (SVD) analyses. The typical timescale of ENSO is estimated to be about 40 months before the late 1970s and 48–52 months after that; the timescale increased by about 10 months. The spatial pattern of the ENSO signal appearing in SST also changed in the 1970s; before that, the area of strong signal spread over the extratropical regions, while it is confined near the equator after that. The center of the strongest signal shifted from the central and eastern equatorial Pacific to the South American coast at that time. These SST fluctuations near the equator are associated with fluctuations of zonal wiond, whose spatial pattern also shifted considerably eastward at that time. In the eastern equatorial Pacific, amplitudes of annual cycles of SST are weak in El Niño years and strong in La Niña years. This relation is not clear, however, in the 1980s and 1990s.