A Narrow Boundary Current Along the Eastern Side of the Hawaiian Ridge; The North Hawaiian Ridge Current

Abstract

Mesoscale baroclinic circulation features in the vicinity of the Hawaiian Ridge are delineated through the construction of the horizontal distribution of mean 300 m temperature on a 0.5° latitude/longitude grid. This high resolution is made possible through the gridding of all XBT observations taken in the area from 1968?80. Of particular interest is the discovery of a narrow band of northward shear flow, extending along the eastern side of the Hawaiian Ridge from 19.5?21.5°N. This band of shear flow has a width of 75?100 km, associated with an estimated near-surface speed (100/400 db) of ?45 cm s?1. This narrow boundary current is associated with recirculation in a small, but intense, anticyclonic gyre that parallels the Hawaiian Ridge; it does not appear to be related to the North Equatorial Current that impinges upon the Hawaiian Ridge from the northeast. Because this current had not previously been observed, it is called the North Hawaiian Ridge Current.