Mesoscale variability in volume transport in the Tasman and Coral Seas

Abstract

Mesoscale variability of volume transports for the upper 450 m of the south-west Pacific is examined with repeat expendable bathythermograph temperature cross-sections, using a level of no motion of 1300 m. Salinity and dynamic heights are synthesized. The 136 sections are clustered about seven particular routes between Australia, Fiji and New Zealand. Peak values of net transports across one- degree latitude or longitude bins along routes are found to be an effective method of defining spatial variability, reflecting current features quite strongly. Higher local transports are indicated along the flanks of Lord Howe Rise, West Norfolk Ridge and parts of Challenger Plateau, emphasizing the topographically controlled nature of the currents. Little seasonality is evident. A very broad mean transport pattern is consistent with results in the literature derived by other methods, as are transports for the East Australian Current, indicating that results are representative. The reliability of the mean pattern is examined in terms of directional persistence, e.g. net outflows to the east are strongly directional north and north-west of New Zealand. Error calculations and an overall regularity of results indicate a valid analysis.