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Large sensitivity to initial conditions in seasonal predictions with a coupled ocean‐atmosphere general circulation model
Author(s) -
Ploshay J. J.,
Anderson J. L.
Publication year - 2002
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2000gl012710
Subject(s) - predictability , climatology , atmosphere (unit) , environmental science , gcm transcription factors , general circulation model , atmospheric model , atmospheric sciences , atmospheric circulation , sea surface temperature , tropical atlantic , ocean current , walker circulation , meteorology , geology , climate change , oceanography , physics , quantum mechanics
An ensemble of one‐year forecasts differing only in details of the atmospheric initial conditions was produced with a coupled ocean‐atmosphere general circulation model (GCM) in order to investigate the predictability of the coupled system. For some ocean initial conditions, the evolution of the tropical Pacific ocean thermal structure seems to be relatively deterministic for lead times out to one year. However, there are other ocean initial conditions, mostly in the mid 1990's for which coupled model forecasts of the tropical Pacific are much more sensitive to details of the atmosphere initial conditions. In some cases, the ensemble forecasts appear to split, with some ensemble members predicting El Niño‐like conditions, and others predicting La Niña. Very large ensembles were run for several of these cases. Very slight perturbations added to the atmospheric initial conditions led to large spread in predicted SST anomalies in some years. These are model results, however, they do suggest the possibility that seasonal predictions of the coupled tropical system may be highly non‐deterministic in some years.