VARIABILITY IN THE SOUTH-PACIFIC DEEP WESTERN BOUNDARY CURRENT FROM CURRENT-METER OBSERVATIONS AND A HIGH-RESOLUTION GLOBAL-MODEL

Observations of the South Pacific Deep Western Boundary Current from t he World Ocean Circulation Experiment Pacific current meter array 9 (W OCE PCM-9) current meter array are compared with the Los Alamos Nation al Laboratory high-resolution global ocean model. A simple integration of PCM-9 velocity yields a mean northward transport of water deeper t han 3000 m that is some 5 times greater than the model mean transport of 3.35 x 10(6) m(3) s(-1). The low modeled abyssal transport suggests a poor simulation of the mean thermohaline circulation. However, mode l and observed transport variability correlate significantly. Space-ti me spectral analysis shows planetary waves are responsible for most of the variability and are resolved well in the model. The details of in teraction of the long waves at the western boundary are different in m odel and data. The model reflects these waves predominantly as planeta ry short waves, which decay over the region 600-800 km east of the Ker madec Ridge. PCM-9 has a higher proportion of energy as topographic wa ves along the Kermadec Ridge. These two classes of waves are associate d with the two observed zonal scales in the boundary current. The mode l results can be separated into vertical modes. Baroclinic energy is f ound at all timescales, including those too short for free baroclinic waves. The baroclinic flow correlates with the barotropic so as to enh ance surface, and reduce abyssal, kinetic energy. This is the signatur e of planetary wave scattering at the submerged western boundary ridge , and results in enhanced baroclinic wave energy in the Tasman Sea.