Interdecadal Variations of ENSO Signals and Annual Cycles Revealed by Wavelet Analysis |
| |
| Authors: | Takashi Setoh Shiro Imawaki Alexander Ostrovskii Shin-Ichiro Umatani |
| |
| Institution: | (1) Department of Earth System and Technology, Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan;(2) Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka, 816-8580, Japan |
| |
| Abstract: | 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. |
| |
| Keywords: | SST zonal wind wavelet analysis equatorial Pacific decadal variation ENSO annual cycle |
| 本文献已被 SpringerLink 等数据库收录！ |
|
