TY - JOUR
T1 - Reassessing the role of stochastic forcing in the 1997-1998 El Niño
AU - Vecchi, Gabriel Andres
AU - Wittenberg, A. T.
AU - Rosati, A.
PY - 2006/1/16
Y1 - 2006/1/16
N2 - We explore the extent to which stochastic atmospheric variability was fundamental to development of extreme sea surface temperature anomalies (SSTAs) during the 1997-8 El Niño. The observed western equatorial Pacific westerly zonal stress anomalies (τax), which appeared between Nov. 1996 and May 1997 as a series of episodic bursts, were largely reproducible by an atmospheric general circulation model (AGCM) ensemble forced with observed SST. Retrospective forecasts using a hybrid coupled model (HCM) indicate that coupling only the part of τax linearly related to large-scale tropical Pacific SSTA is insufficient to capture the observed 1997 warming; but, accounting in the HCM for all the τa x that was connected to SST, recovers most of the strong SSTA warming. The AGCM-estimated range of stochastic τ ax forcing induces substantial dispersion in the forecasts, but does not obscure the large-scale warming in most HCM ensemble members.
AB - We explore the extent to which stochastic atmospheric variability was fundamental to development of extreme sea surface temperature anomalies (SSTAs) during the 1997-8 El Niño. The observed western equatorial Pacific westerly zonal stress anomalies (τax), which appeared between Nov. 1996 and May 1997 as a series of episodic bursts, were largely reproducible by an atmospheric general circulation model (AGCM) ensemble forced with observed SST. Retrospective forecasts using a hybrid coupled model (HCM) indicate that coupling only the part of τax linearly related to large-scale tropical Pacific SSTA is insufficient to capture the observed 1997 warming; but, accounting in the HCM for all the τa x that was connected to SST, recovers most of the strong SSTA warming. The AGCM-estimated range of stochastic τ ax forcing induces substantial dispersion in the forecasts, but does not obscure the large-scale warming in most HCM ensemble members.
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U2 - 10.1029/2005GL024738
DO - 10.1029/2005GL024738
M3 - Article
AN - SCOPUS:33644624498
SN - 0094-8276
VL - 33
JO - Geophysical Research Letters
JF - Geophysical Research Letters
IS - 1
ER -