Mean annual sea surface temperatures in New Zealand waters

The long term annual mean is derived from 240 monthly mean sea surface temperature (SST) analyses, which in turn is used to specify the year to year anomalies in SST, both as mapped spatial values at 1 km resolution, and aggregated by Tasman Sea, Sub-Tropical and Sub Antarctic Waters water masses. For reference the aggregated mean SST anomaly over the whole New Zealand region (approximately 2,600 × 2,600 km2) is also indicated.

Tasman sea, Sub-tropical waters (STW), Southern Antarctic waters (SAW) and total area for the New Zealand region.

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The ocean waters surrounding New Zealand vary in temperature from north to south. They interact with heat and moisture in the atmosphere and affect our weather. Sea surface temperature changes with climate drivers such as El Niño, and will change with climate change. The sea surface temperature anomaly provides an indication of the heat change in the ocean.
Long-term changes and short-term variability in sea-surface temperatures can affect marine processes, habitats, and species. Some species may find it hard to survive in changing environmental conditions.

The New Zealand region encompasses our exclusive economic zone (EEZ), the Chatham Rise, northern subtropical waters, subantarctic waters, and the Tasman Sea. It extends from about 30°S to 55°S, 160°E to 170°W.
NIWA’s sea-surface temperature archive (NSA) is derived from the Advanced Very High Resolution Radiometer (AVHRR) data it receives from the National Oceanic and Atmospheric Administration satellites. The archive provides high spatial (approximately 1km) and high temporal (approximately 6-hourly in cloud-free locations) resolution estimates of sea-surface temperatures over the New Zealand region, dating from January 1993. Uddstrom and Oien (1999) and Uddstrom (2003) describe the methods used to derive and validate the NSA. Datasets with longer time series are available. This dataset has been selected because it represents the New Zealand region and the spatial variability of temperatures in our waters.