THE EFFECTS OF SHEAR-FLOW ON PROPAGATION OF ROSSBY WAVES IN THE EQUATORIAL OCEANS

The effects of strong meridional shear of mean flow on propagation of long waves having a wavelength of about 1000 km and period of 25 days observed in the equatorial Pacific and Atlantic Oceans are analyzed in this paper. Information from the weekly multichannel sea surface temp erature images derived from the Advanced Very High Resolution Radiomet er on board the NOAA series satellites from January 1986 to March 1999 is used for the statistics of the visual parameters of the waves. The characteristic scales of the waves are estimated based on the results by previous investigators and the statistical results of the present study. Solving a potential vorticity equation, the authors obtain a di spersion relation with an additional term depending on the flow shear strength compared with that of the free Rossby wave. The theoretical m odel provides a good explanation for the variable behavior of long-wav e propagation.