Characteristics of interleaving in the western equatorial Pacific

Abstract

The characteristics of intrusive thermohaline features in the thermocline of the western equatorial Pacific are examined during two different climatic states. The vertical and meridional structure of the features is determined from a total of 12 high-resolution meridional sections. Although there is considerable variability of the broader structure of the flow and temperature/salinity fields, the spatial scale of the interleaving is found to be persistent over all sections. The Turner angle and correlations between the spice anomaly and density anomaly suggest that double-diffusive processes may be important in the vertical flux of properties. The characteristics of the interleaving are compared with the results from the theories of double-diffusive interleaving and intertial instability. It is found that the observations are consistent with both. It is difficult to differentiate between the two theories in explaining the presence of the layers. Indeed, both mechanisms may be playing a role. The magnitude of the cross-equatorial fluxes of heat and salt due to the features is estimated and shown to be comparable with estimates due to other processes. There is a strong potential for the interleaving to impinge on the large-scale dynamics of the equatorial Pacific Ocean.