Detection of equatorial waves in the indian ocean using topex/poseidon and noaa/avhrr

This study used 1993-1997 data of sea surface height (SSH) from TOPEX/POSEIDON and sea surface temperature (SST) from NOAA AVHRR to detect equatorial waves in the Indian Ocean between 10°S-10ºN, 30°-120°E. A two-dimensional Fast Fourier
Transform (FFT) was applied to the SSH and SST data sets in order to investigate the amplitudes, periods, wavelength, and phase speeds of the equatorial waves.
Rossby waves of annual period were found at 10°-5ºS and semi-annual baroclinic Rossby waves were found around the equator from both SSH and SST. Linear regression analysis between the phase speeds derived from SSH and SST shows coefficient of correlation of - 0.5. The phase speeds derived from SSH increase toward the equator for both annual and semi-annual waves while the speeds from SST shows an increase toward the equator only for the semi-annual waves.
Cross-correlation analysis was applied to SSH and SST fields. The correlations obtained may be overestimated as significance tests have not been applied; however, high
correlations of greater than 0.5 were found at south of 7ºS.