The role of transient eddies in modulating the high southern latitude ENSO teleconnection during strong SAM events

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Tuesday, 19 January 2010: 11:45 AM
B215 (GWCC)
Ryan L. Fogt, Ohio University, Athens, OH; and D. H. Bromwich and K. M. Hines

High latitude South Pacific El Niño – Southern Oscillation (ENSO) teleconnection variations during phases of the Southern Hemisphere Annular Mode (SAM) events are examined. The focus is on multi-month, multi-event variations during the last 30 years. The study finds that when La Niña (El Niño) events occur with a positive (negative) SAM phase, the South Pacific pressure anomalies—lower in La Niña / SAM positive, higher in El Niño / SAM negatve--remain statistically different than climatology. In other simultaneous combinations, the South Pacific pressure anomalies are weak and insignificant. The talk will demonstrate that these dramatic changes are related to significant interactions between the ENSO and SAM transient eddies which alter the zonal mean flow and the high southern latitude pressure response. The findings suggest that if SAM and ENSO can be accurately predicted, then more reliable estimates of the South Pacific teleconnection magnitude and position, and therefore its impacts on Southern Ocean and Antarctic climate, can be generated.