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Recent forecast skill for the El Niño/Southern Oscillation
Author(s) -
Ghil Michael,
Jiang Ning
Publication year - 1998
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 - 10.1029/97gl03635
Subject(s) - predictability , climatology , el niño southern oscillation , oscillation (cell signaling) , southern oscillation , forecast skill , multivariate enso index , madden–julian oscillation , sea surface temperature , series (stratigraphy) , scalar (mathematics) , environmental science , meteorology , geology , mathematics , physics , statistics , convection , paleontology , geometry , biology , genetics
We outline a relationship between three slowly varying characteristics of the coupled ocean‐atmosphere system in the tropical Pacific: (i) quasi‐periodicity, (ii) extended predictability, and (iii) approximate low dimensionality. The Southern Oscillation Index (SOI) and Niño‐3 sea surface temperatures characterize climatic variations in the tropical Pacific; these two time series are usually anticorrelated. This low‐dimensional characterization suggests that much of the system's seasonal‐to‐interannual predictability depends on the regular behavior of the two scalar time series under consideration. The predictive skill of two idealized models is studied, showing the strong connection between regularity and predictability. El‐Niño/Southern‐Oscillation (ENSO) predictability is then assessed for current forecast models. When the periodic component of the ENSO signal is strong, it results in higher forecast skill. This skill decreases when the anti‐correlation between SOI and Niño‐3 temperature anomalies is lost, as it has been in the first half of this decade.