Global eastward propagation signals associated with the 4–5-year ENSO cycle
- 302 Downloads
Longitude-time evolution of sea surface temperature anomalies (SSTA) reveals a slow southeastward propagation from the western North Pacific (WNP) around 20°N to the Niño-3.4 region in the equatorial Central Pacific. The propagation is manifested as a narrow, southwest-northeast oriented SSTA band across the subtropical North Pacific, and its journey takes about 2–3 years. The propagating SSTA appears to engage the initiation of the El Niño–Southern Oscillation (ENSO). The anomalies of surface winds, sea level pressure, outgoing longwave radiation, and velocity potential all exhibit a concurrent and distinct eastward propagation, one that appears to be circumglobal and is coupled with the predominant 4–5 year frequency of the ENSO cycle. It is suggested that the previously found warming/cooling in the Indian Ocean induced by El Niño/La Niña, the progressive SSTA and wind anomalies across the Indian Ocean towards the WNP, and the predominant 4–5-year frequency of the North Pacific Oscillation collectively contribute to the reported SSTA propagation . The findings implicate that monitoring the SSTA propagation from the WNP towards the tropical central Pacific could be useful in tracking the ENSO development.
KeywordsENSO cycle SST propagation Precursor Prediction WNP
Useful discussions with Michelle L'Heureux and TC Chen are highly appreciated. This study was supported by the NASA Grant NNX13AC37G and by the United States Agency for International Development Grant EEM-A-00-38310-00001.
- Anderson BT (2003) Tropical Pacific sea surface temperatures and preceding sea level pressure anomalies in the subtropical North Pacific. J Geophys Res 108(D23). doi: 10.1029/2003JD003805
- Clarke AJ (2008) An introduction to the dynamics of El Nino and the Southern oscillation. Academic Press, London, p 308Google Scholar
- Walker GT, Bliss EW (1932) World weather V. Mem Roy Meteor Soc 4:53–84Google Scholar
- Wang S-Y, L’Heureux M, Chia H-H (2012) ENSO prediction one year in advance using western North Pacific sea surface temperatures. Geophys Res Lett 39(5):L05702Google Scholar