J13.3
The termination of the 2002-3 El Niņo
Gabriel A. Vecchi, JISAO/Univ. of Washington, Seattl, WA; and D. E. Harrison
Every new El Niņo presents an opportunity to revisit our understanding of El Niņo characteristics and processes. We examine the extent to which the termination of the 2002-03 El Niņo followed the scenario of Harrison and Vecchi [1999], in which (1) there is a late-year southward shift of near-equatorial westerly wind anomalies, and (2) subsequent eastern equatorial Pacific cold tongue thermocline shallowing is driven by the wind shift. There was a prominent late-year southward shift in the low-frequency west Pacific zonal wind anomalies in 2002-03. Ocean general circulation model experiments establish the shift as the primary cause of cold tongue thermocline shallowing. Reflected equatorial waves and local wind anomaly changes are much less important. Successful theories and models of El Niņo should address the processes that cause the year-end southward wind shift. Interactions between anomalous El Niņo conditions and the seasonal cycle of solar insolation may provide such a process.
Joint Session 13, Seasonal to interannual climate prediction with emphasis on the 2002 El Nino (Joint with 15th Symp. on Global Change and Climate Variations and the Symp. on Forecasting Weather and Climate of the Atmosphere and Ocean (Room 6C)
Thursday, 15 January 2004, 8:30 AM-4:30 PM, Room 6C
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