| TOPEX/POSEIDON (T/P) sea level deviation (SLD) time series from October 3, 1992 to May 15, 1997 combined with ERS-1/2 and NASA Scatterometer winds from May 3, 1992 to June 17, 1997, tide gauge measurements, and upper ocean thermal structures are used to observe the characteristics and analyze the dynamics of equatorial waves in the Pacific Ocean. The Complex Singular Value Decomposition method is applied to SLD time series for revealing the dynamics of equatorial waves. The results give the zonal and meridional structures, propagation directions, and propagation speeds of equatorial waves. The phase speed of the Kelvin wave is 2.5 ms{dollar}sp{lcub}-1{rcub}{dollar}, and that of the Rossby waves are {dollar}-{dollar}0.6 ms{dollar}sp{lcub}-1{rcub}{dollar} within 4-6{dollar}spcirc{dollar}N and {dollar}-{dollar}0.4 ms{dollar}sp{lcub}-1{rcub}{dollar} within 6-8{dollar}spcirc{dollar}S, respectively. The meridional structure of a Rossby wave is asymmetric to the equator with higher amplitude in the north than in the south.; The evolution of the Kelvin wave propagating along an eastward shoaling thermocline in the equatorial Pacific is investigated. The behavior of this wave as it propagates eastward can be described with the solutions of the perturbed Korteweg-de Vries (PKdV) equation and modified Green's Law. Assuming that the nonlinear and dispersive terms are balanced, the amplitude increases as the thermocline decreases to the power of 3/8. Approaching the eastern Pacific, the nonlinearity increases and the relation changes to the power 9/8. The dispersion relation, and mass and energy conservations are investigated. The results indicate that under a varying thermocline, the nonlinear Kelvin solitary waves indeed exist in the real ocean.; Time-frequency analysis of the T/P SLD time series along the equator and 5{dollar}spcirc{dollar}N using the Empirical Mode Decomposition-Hilbert Spectrum shows that a nonlinear interannual Kelvin wave is characterized by an intra-frequency modulation with a mean frequency {dollar}(215pm 10) times 10sp-5{dollar} cpd or 16-month period. The annual nonlinear Rossby wave is characterized by an intra-frequency modulation with a mean frequency {dollar}(295pm 10) times10sp{lcub}-5{rcub}{dollar} cpd or one-year period. The total of the projected-zonal westerly wind stress is used to represent wind forcing. The interannual nonlinear downwelling Kelvin wave in the central and eastern Pacific is remotely generated by westerly wind forcing and carries warm water from the western Pacific to the east associated with the El Nino event. This research gives a greater insight into the cause of the onset of the El Nino event. |
