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Advanced Very-High Resolution Radiometer (AVHRR) images of sea surface temperature (SST) in the New Zealand region have been archived since 1989. The first 2 years of data are used to investigate the variability in sea surface temperature (SST) and its gradients around New Zealand. Empirical orthogonal function (EOF) analyses show that the annual cycle accounts for 92% of the variance of SST, but for less of the variance in SST gradient. The Southland and Subantarctic Fronts have an annual modulation in their strengths, accounting for about 20% of their variance; these modulations are out of phase, with the Southland Front being strongest in winter. The Subtropical Convergence shows variability that cannot be easily described by one mode, but appears to migrate meridionally with an annual period, being furthest north in March.