CoAuthors

Ted Durland (Oregon State University, USA); Steven Jayne (Woods Hole Oceanographic Institution, USA)

Analysis of sea-surface height (SSH) anomalies from satellite altimetry shows variability throughout much of the North Pacific that is coherent with tropical instability waves. This variability has regular phase patterns that are consistent with barotropic Rossby waves having northward energy propagation, and the waves can be clearly seen to propagate from the equatorial region to at least 30N. Comparisons with numerical simulations support the conclusion that this remote variability can indeed be attributed to barotropic Rossby waves generated near the equator. Near 40N, the SSH field remains coherent with the near-equatorial SSH variability, but it is not as clear whether the variability at the higher latitudes is a simple result of barotropic wave radiation from the tropical instability waves; for example, there is some wind variability at the higher latitudes that is coherent with both the local SSH and the TIWs near the equator.

These barotropic Rossby waves contribute to the mesoscale variability in SSH in the midlatitudes. This variability is not well represented in the widely used AVISO gridded SSH products, and this appears to be a result of the assumed form of the autocovariance function used for the objective mapping scheme.