Extended Abstract (488K)J3.3
Decadal variability of the ENSO teleconnection to the South Pacific governed by coupling with the Antarctic Oscillation
Ryan L. Fogt, Byrd Polar Research Center, Ohio State Univ., Columbus, OH; and D. H. Bromwich
Decadal variability of the ENSO teleconnection to the South Pacific (~60oS, 120oW) is examined using the ERA-40 reanalysis and observations over the last three decades. There is a sharp contrast between the 1980s and the 1990s, with the teleconnection in the 1990s being significantly amplified. The annual teleconnection is dominated by the strong response during austral spring and summer. In particular, the teleconnection in the 1990s was stronger than in the 1980s due to an enhanced response during austral spring.
Principal Components Analysis (PCA) is performed on seasonal anomalies of the 500 hPa geopotential height fields to isolate the mechanisms causing the decadal change. In SON, PCA reveals that the 1980s teleconnection is weak due to the interference between the Pacific South American pattern (PSA) associated with ENSO and the Antarctic Oscillation (AAO) pattern, especially during the 1988 La Niņa. Regression analysis details that in the 1990s SON the AAO is strongly coupled with the central equatorial Pacific SST anomalies; the AAO is in-phase with the ENSO forcing during this decade producing a strong teleconnection. The in-phase relationship between the tropical and high latitude forcing also exists in DJF during the 1980s and 1990s. Thus, the significantly positive correlation between ENSO and the AAO only during times of strong teleconnection suggest that both the tropics and the high latitudes need to work together in order for ENSO to strongly influence Antarctic climate.
Joint Session 3, Climate of the Southern High Latitudes (Joint Session with the Eight Conference on Polar Meteorology and the 16th Conference on Climate Variability and Change) ( parallel with Session 14)
Thursday, 13 January 2005, 11:00 AM-12:15 PM
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