SEA-LEVEL VARIABILITY ON THE WEST-COAST OF NEW-ZEALAND

Variations in coastal sea level in the weather band (periods 5-20 days ) on the west coast of New Zealand can largely be explained in terms o f wind-forced coastal-trapped waves. Long-wave theory was applied to t he North island shelf with some success in hindcasting sea level at Ne w Plymouth. On the southern South Island shelf, the sea level signal w as found to propagate like a mode-one coastal-trapped wave, but the co mplex topographic variations made application of simple long-wave theo ry impossible. The sea level signal in the south of the region was hig hly correlated with alongshore wind stress over the shelf region to th e north, suggesting that alongshore wind stress is the major forcing m echanism. In contrast, the generation of coastal-trapped waves by a co astal flux through Taranaki Bight/Cook Strait appears to be the domina nt mechanism over the northern and central South Island shelf, from th e present and previous studies.