VARIABILITY IN SEA-SURFACE TEMPERATURE AROUND NEW-ZEALAND FROM AVHRR IMAGES

Multi-channel Advanced Very-High Resolution Radiometer (AVHRR) images of sea surface temperature (SST) in the New Zealand region have been a rchived since 1989. The first 2 years of data are used to investigate the variability in sea surface temperature (SST) and its gradients aro und New Zealand. Empirical orthogonal function (EOF) analyses show tha t the annual cycle accounts for 92% of the variance of SST, but for le ss of the variance in SST gradient. The Southland and Subantarctic Fro nts have an annual modulation in their strengths, accounting for about 20% of their variance; these modulations are out of phase, with the S outhland Front being strongest in winter. The Subtropical Convergence shows variability that cannot be easily described by one mode, but app ears to migrate meridionally with an annual period, being furthest nor th in March.