| The observational data set archived by the Permanent Service for Mean Sea Level (PSMSL) consists of monthly means of sea-level heights at 846 stations. 213 of them are suitable for our purposes. We identified two dominant time scales of El Nino-Southern Oscillation (ENSO) signal, as quasi-biennial and low-frequency (LF) at almost all stations, with the highest amplitudes in the equatorial Pacific and along the west coast of North America. Global sea-level rise, after post-glacial rebound corrections, are 1.620.38 mm/yr.; Propagation features of the interannual variability are studied along the coastal sea level stations in five regions: eastern, western, and equatorial Pacific; eastern and western Atlantic. Throughout the Pacific, three dominant spatio-temporal oscillatory patterns are found in the time scales of ENSO variability. In the eastern Pacific, the biennial mode and the 6-yr low-frequency mode propagate poleward. In the western Pacific, interannual oscillation propagates southward in the northern hemisphere but no clear propagation is observed in the southern hemisphere. Equatorward propagation of the biennial signal is very clear in each hemisphere. In the equatorial Pacific, both the quasi-quadrannial and quasi-biennial modes at 10{dollar}spcirc{dollar}N propagate westward. Strong and weak El Nino years are evident in RSLH reconstructed from the biennial and low-frequency modes. Interannual variability with periods of 3 and 4-8 years is detected in the Atlantic RSLH data. In the eastern Atlantic region, we have found slow propagation of both modes northward and southward, away from 40-45{dollar}spcirc{dollar}N.; Sufficiently long and continuous RSLH at 81 stations show interdecadal oscillations with the periods of 9-13 and 18 years. 11.6 and 12.8 years of oscillations are found in the eastern and western Atlantic ocean at latitudes 40{dollar}spcirc{dollar}N-70{dollar}spcirc{dollar}N and 10{dollar}spcirc{dollar}N-50{dollar}spcirc{dollar}N, respectively.; The aforementioned features are simulated with a wind driven ocean model for the periods of 1950 and 1992. Comparisons of the observed and simulated RSLH indicate that the model captures most of the intraseasonal and interannual variability at low latitudes and along the eastern boundaries, but not in the western boundaries. Since some of the interannual variability and their propagative features agree with the observations the wind-driven, reduced gravity model suffice to investigate the oscillatory features of interannual variability in low latitudes and eastern ocean basins. |
