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40–60 day oscillations in the western tropical Pacific: Results from an eddy‐resolving global ocean model
Author(s) -
Ponte Rui M.,
Gutzler David S.
Publication year - 1992
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 - 10.1029/92gl01640
Subject(s) - climatology , geology , amplitude , zonal and meridional , ocean general circulation model , oscillation (cell signaling) , atmospheric sciences , wind stress , instability , atmosphere (unit) , oceanography , general circulation model , climate change , meteorology , physics , quantum mechanics , biology , mechanics , genetics
Preliminary analyses of results from the Semtner and Chervin [1992] eddy‐resolving general circulation model reveal the presence of energetic 40–60 day oscillations in the near‐surface layers of the western tropical Pacific. These oscillations have the strongest signal in meridional velocity (maximum amplitudes on the order of 10–20 cm s −1 ), in latitudinal bands west of the dateline centered at approximately 10°N and 10°S. The 40–60 day disturbances have zonal wavelengths of approximately 700 km at 10°N and 1000 km at 10°S, and show clear westward phase propagation at speeds of order 15–20 cm/s. Eastward (but slower) energy propagation is also apparent. The oscillations in the model are a result of oceanic instability processes and not a direct response to wind stress anomalies associated with the Madden‐Julian oscillation in the atmosphere. Enhanced energy at 40–60 days is also present in the Indian and Atlantic basins, suggesting that the 40–60 day time scale is a preferred scale for variability in the tropical oceans.