New Zealand Journal of Marine and Freshwater Research abstracts
Salinity variability in shelf waters near Otago Peninsula, New Zealand, on a time scale of hours
DAVID J.HAWKE
Department of Chemistry University of Otago P. O. Box 56 Dunedin, New Zealand
Present address: Department of Chemistry, University of Canterbury, Christehurch 1, New Zealand.
Abstract
A transect crossing the continental shelf adjacent to Otago Peninsula was occupied on six occasions each for c. 8 h. Substantial variability in both high-salinity and low-salinity waters was found. On five occasions, a clearly identifiable low-salinity pulse, which took less than a tidal cycle to pass the transect, was observed. No correlation with any part of the tidal cycle was identified. These low-salinity events are probably generated by ebb tide release of water from the Clutha River. The position and form of the surface salinity minimum across the continental shelf was highly variable on occasion. Movement up to 3 km cross-shelf, splitting into two minima, and the combining of two minima were events observed within the timescale of the observations. The results allow prediction of salinity minimum off Otago Peninsula over a Clutha River flow range of 500-1000 m
3 s-
1:
S = -0.00201
F + 35.53, where
S = salinity minimum (psu) and
F = mean daily Clutha River flow 4-12 days earlier (m
3 s"
1).
Keywords continental shelf; salinity; spatial and temporal variability; Clutha River; Otago Peninsula; South Island
M92OO1
Received 9 January 1992; accepted 6 March 1992
New Zealand Journal of Marine and Freshwater Research, 1992, Vol. 26:The Royal Society of New Zealand 1992
Recieved 9 January 1992, accepted 6 March 1992
PDF file of entire paper: medium quality (606K); (scanned from paper original: notes about this process)
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