Butler et al. - Subtropical Convergence Zone oceanography

New Zealand Journal of Marine and Freshwater Research abstracts

Oceanography of the Subtropical Convergence Zone around southern New Zealand

E. C. V. BUTLER J. A. BUTT E.J.LINDSTROM1 P. C. TILDESLEY

CSIRO Division of Oceanography Marine Laboratories, P. O. Box 1538 Hobart, Tasmania 7001, Australia

S. PICKMERE W.F.VINCENT2

Taupo Research Laboratory
DSIR Marine and Freshwater
Department of Scientific and Industrial Research
P. O. Box 415, Taupo, New Zealand
'Present address: Interagency Office for WOCE, 1755 Massachusetts Ave. NW, Suite 700, Washington DC 20036, U.S.A.
2Present address: Department de biologie, University Laval, Qu6bec G1K 7P4, Canada.

Abstract Seawatersofthe Subtropical Convergence Zone around the south of New Zealand were surveyed concurrently by two research ships in May 1989. The general surface features of the region are depicted in remotely sensed images of sea-surface temperatures obtained at the time of the survey, and also from preceding years. Shipboard data, obtained underway and on station, are used to describe the water masses and frontal structures. Short-term variability is discussed where stations were re-occupied after an interval of several days. Apositive gradient of nutrient concentration was observed when proceeding from subtropical to subantarctic waters. This general trend is modified in coastal regions by freshwater run-off, and by mixing processes in open ocean waters. It is suggested that possible mechanisms for the nutrient enrichment of surface waters, leading to enhanced biological productivity, are horizontal advection, and uplifting of subsurface waters - coupled with deep mixing events or influenced by the continental slope. It seems that all of these processes may be variable and sporadic; no sustained process such as upwelling was observed in the region.

Keywords biological production; chemical oceanography; Foveaux Strait; iodine; nutrients; Puysegur Bank; remote sensing; salinity; Snares Shelf; Solander Trough; spatial and temporal variability; Southland Front; temperature

New Zealand Journal of Marine and Freshwater Research, 1992, Vol. 26:The Royal Society of New Zealand 1992
Received 2 August 1991; accepted 8 April 1992

PDF file of entire paper: medium quality (3955K); (scanned from paper original: notes about this process)

This year's abstracts | Journal home page | All abstracts | Publishing home page