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Non‐linear alignment of El Niño to the 11‐yr solar cycle
Author(s) -
White Warren B.,
Liu Zhengyu
Publication year - 2008
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 - 10.1029/2008gl034831
Subject(s) - la niña , climatology , el niño southern oscillation , multivariate enso index , forcing (mathematics) , harmonics , solar cycle , atmospheric sciences , oscillation (cell signaling) , environmental science , physics , geology , plasma , solar wind , chemistry , biochemistry , voltage , quantum mechanics
El Nino/La Nina episodes represent warm/cool phases of 2‐ to 7‐yr period El Nino‐Southern Oscillation (ENSO) in the tropical Pacific ocean‐atmosphere system. Modeling studies find ENSO self‐excited or driven by ambient noise. Here we find most El Nino and La Nina episodes from 1900–2005 grouped into non‐commuting pairs that repeat every ∼11 yrs, aligned with rising and falling transition phases of the ∼11‐yr period quasi‐decadal oscillation (QDO). These alignments arise from non‐linear phase locking of 3rd and 5th harmonics near 3.6‐ and 2.2‐yr to the 1st harmonic near 11‐yr period. Here we find these alignments replicated in both coupled general circulation model and conceptual model driven by 11‐yr solar forcing, wherein the solar‐forced 1st harmonic initiates a non‐linear cascade of higher odd harmonics that are phase‐locked with the same alignments as observed. These solar‐forced 3rd and 5th harmonics explain ∼52% of inter‐annual variance in the Nino‐3 temperature index from 1900–2005.