Sea level variations in the tropical Pacific Ocean during two types of recent El Niño events
2013
Chang, Yi-Ting | Du, Ling | Zhang, Shou-Wen | Huang, Peng-Fei
Sea level variations in the tropical Pacific Ocean (TPO) exhibit the prominent periods of 30 and 52months on interannual timescale, and the interannual variance illustrates the geographical distribution over the 1993–2010 period. The quasi-biennial amplitude is comparable to the seasonal variation in the east off the Philippine coast (EOP). The Central Pacific El Niño (CP El Niño) events have occurred frequently and comparably in the satellite altimetry era compared with the Eastern Pacific El Niño (EP El Niño), and the sea level varies closely related to the two types of El Niño events. A see–saw mode of sea level is dominant during the EP El Niño event, but a “shuttle” pattern towers mainly in the central equatorial Pacific during the CP El Niño events. The oceanic and atmospheric processes interpret the sea level evolution during the CP El Niño and the EP El Niño events. Sea level variations in the EOP are impacted by the local and remote responses of atmospheric wind fields. The remote effect caused by the westward Rossby wave dominates in the atmospheric contribution which is nearly twice the magnitude of the local Ekman pumping effect. The local wind contributes to sea level evolution primarily in the beginning of the El Niño events. The remote process of the Rossby wave persists in 35% of the three CP El Niño phases, while the predicted skill distribution, about 43—53%, maps geographical variability in the EP El Niño event.
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