The Identification and Nomenclature of the Surface Water Masses in the Tasman Sea (Data to the End of 1954)

Abstract

In this paper an examination of all available data on the hydrological characteristics of the Tasman Sea, prior to and including the year 1954, has permitted the identification and naming of eight surface water masses. Certain of their properties and general features of their season and region of occurrence and method of formation are summarized.

Although little quantitative data are available some general features of the circulation of these water masses in the Tasman Sea are deduced from a study of their seasonal occurrence in relation to source regions.

The Coral Sea water mass (chlorinity 19.60-19.70‰, temperature 20-26º C) flows from a source region in the north-west Coral Sea along the western side of the Tasman Sea and reaches maximum velocity off Sydney in October-December. The South Equatorial (chlorinity 19.50-19.60‰, temperature 24-26º C) also flows south along the western side of the Tasman Sea but reaches maximum velocity between February and March. These two water masses constitute the East Australian current.

The Sub-Antarctic (chlorinity 19.15-19.30‰, temperature 10-14°C) is found at the surface in the south-eastern Tasman Sea between July and September. The Central Tasman (chlorinity 19.65-19.75‰, temperature 15-20‰C) flows to the west from its region of formation and generally flows north along the southern New South Wales coast in late winter. The South-west Tasman (chlorinity 19.50- 19.60‰, temperature 12-15°C) flows to the east in latitude 38ºS. and curves south in a clockwise gyral off eastern Tasmania between October and December. The Xorth Bass Strait (chlorinity 19.66-19.75‰ temperature 12-17ºC) flows from South Australia to the eastern approaches of Bass Strait. The East Central New Zealand (chlorinity 19.10-19.30‰, temperature 15-20°C) flows west through Cook Strait into the Tasman Sea in midsummer. The East and West Tasmanian (chlorinity 19.40- 19.50‰ temperature 10-14°C) form in midwinter in the southern part of Bass Strait and flow along the east and west coasts in the spring.