Available
surface drifter data are analyzed to determine the characteristics of the
North Hawaiian Ridge Current (NHRC) and its relation to the ocean circulation
around the Hawaiian waters. The NHRC is found to exist as a mean entity along
the coasts of the Hawaiian Islands. It originates as a northern branch of
westward moving interior flow and flows coherently along the islands at an
average speed of 0.10–0.15 m s
1.
The NHRC veers westward at the northern tip of the Hawaiian Islands, and
its subsequent path is not influenced by the presence of the submerged Hawaiian
Ridge. This finding does not support the theory that the NHRC is forced by
westward propagating, baroclinic Rossby waves reflecting off the Hawaiian
Ridge. Using a 2½-layer reduced gravity model of the North Pacific, it is
shown that the mean NHRC is due primarily to the mean rather than the time-varying
wind forcing. The NHRC exists due to the imbalance between the interior Sverdrup
transport and the net southward transport, constrained by the presence of
the Hawaiian Islands. The path and transport of the observed NHRC are found
to be consistent with the flow pattern proposed by this theory.