40–60 day oscillations in the western tropical Pacific: Results from an eddy‐resolving global ocean model

Author: Rui M. Ponte and D.S. Gutzler
Date: 
June 16, 1992
Type: 
Journal Article
Venue: 
Journal of Geophysical Research
Citation: 

Ponte, R. M., and D. S. Gutzler (1992), 40–60 day oscillations in the western tropical Pacific: Results from an eddy‐resolving global ocean model, Geophys. Res. Lett., 19(14), 1475–1478, doi:10.1029/92GL01640.

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.

 

Collaberated on at the Equatorial Theoretical Panel Meeting of July 1991.

Ponte, R.M., and Gutzler, D.S., 1991. 40-60 day oscillations in the western tropical Pacific: Results from the Semtner-Chervin model. Equatorial Theoretical Panel Meeting, University of Rhode Island, July 1991.