A study of coastally trapped, intraseasonal waves of equatorial origin in the global oceans using TOPEX/Poseidon altimeter data

A Multi-channel Singular Spectrum Analysis (MSSA) technique is used to study the propagation of intraseasonal signals eastward in the equatorial waveguides and poleward in the coastal waveguides. Poleward propagation in the coastal waveguides of equatorial signals is observed with TOPEX/Poseidon sea surface height data in the Pacific, Indian, and Atlantic Ocean basins from May, 1993 to May, 1998. A lagged correlation analysis is used to determine the equatorial and coastal phase speeds for identified events. The strongest equatorial Pacific signals propagate at about 2.5 m s−1, commensurate with first mode baroclinic Kelvin waves. The average phase speed of all freely propagating equatorial Pacific events is 2.96 ± 0.49 m s−1. Indian and Atlantic results show equatorial propagation speeds of 2.61 ± 0.39 m s−1 and 2.66 ± 0.63 m s−1 respectively. The observed Pacific coastal phase speeds are 2.95 ± 0.46 m s−1 (northern hemisphere) and 2.87 ± 0.49 m s−1 (southern hemisphere). These results agree well with 3.08 m s−1 observed off of the coasts of Peru and Chile by Shaffer et al., 1997. Observed Indian Ocean coastal phase speeds are 3.02 ± 0.55 m s−1 and 3.39 ± 0.47 m s−1 for the northern and southern hemispheres respectively. A faster propagation speed of 6.42 ± 0.55 m s−1 is observed in the northern Atlantic. The observed southern Atlantic phase speed is 1.52 ± 0.54 m s −1 commensurate with a second baroclinic mode Kelvin wave. The extent of propagation is examined and events are observed to propagate far into the coastal waveguides for all basins except the southern hemisphere Atlantic where propagation is observed to 16°S. South of 18°S, the Benguela current is thought to disrupt local upwelling enough to terminate propagation. Comparisons with wind stress indicate that Pacific and Indian events are primarily caused by wind bursts and Atlantic events by a combination of wind bursts and other mechanisms. This dissertation documents that an active oceanic teleconnection exists between the equator and mid-latitudes in all major ocean basins.