Variability of water masses through the Mernoo Saddle, South Island, New Zealand

Abstract

The Mernoo Saddle is situated c. 100 km east of Banks Peninsula, Canterbury, New Zealand at 44°S 174°E. The Saddle separates the South Island of New Zealand from an underwater ridge known as the Chatham Rise. The Rise acts as a partial barrier to the flow of the subantarctic surface water mass (SAW) and the subtropical surface water mass (STW), which are part of the global Subtropical Front extending around the Southern Ocean. This study examined the variability of the water masses flowing through the Mernoo Saddle using a 3‐year data set of Advanced Very High Resolution Radiometer (AVHRR) Sea Surface Temperature (SST) imagery. This investigation revealed that SAW extended north through the western edge of the Mernoo Saddle for most of the year, however in winter and early spring a southward extension of STW was observed.