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The response of an ENSO Model to climate noise, weather noise and intraseasonal forcing
Author(s) -
Roulston Mark S.,
Neelin J. David
Publication year - 2000
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 - 10.1029/2000gl011941
Subject(s) - climatology , environmental science , forcing (mathematics) , noise (video) , white noise , el niño southern oscillation , climate model , atmospheric noise , sea surface temperature , range (aeronautics) , multivariate enso index , atmospheric sciences , meteorology , climate change , southern oscillation , infrasound , geology , geography , oceanography , physics , mathematics , artificial intelligence , computer science , image (mathematics) , statistics , materials science , composite material , acoustics
The response of an intermediate coupled model of the tropical Pacific to different forms of stochastic wind forcing is studied. An estimate of observed Pacific wind variance that is unrelated to Pacific sea surface temperature (SST) has a red spectrum, inconsistent with standard definitions of “weather noise”. The reddening is likely due to SST outside the basin; we propose a definition of “climate noise” for such reddened variance. Effects are compared for (i) red climate noise; (ii) the corresponding white weather noise estimate; (iii) intraseasonal and interannual components of the white noise (to test frequency response); and (iv) a noise product with extra power in the 30–60 day range. Power is not effectively channeled from subannual frequencies to the frequencies associated with ENSO in this model. This suggests that ENSO impacts of the Madden‐Julian oscillation are largely restricted to the low‐frequency tail rather than the 30–60 day spectral peak. Interannual climate noise originating outside the tropical Pacific appears important.