New Zealand Journal of Marine and Freshwater Research abstracts
Numerical investigation into the effect of freshwater inputs on the
circulation in Pelorus Sound, New Zealand
ROGER PROCTOR
Proudman Oceanographic Laboratory
Bidston
Observatory
Birkenhead, Merseyside L43 7RA
United Kingdom
MARK HADFIELD
National Institute for Water & Atmospheric
Research Ltd
P. O. Box 14 901
Wellington, New Zealand
Abstract Observations collected in Beatrix Bay, a small bay
within Pelorus Sound, New Zealand, show that although the bay is thermally
stratified for much of the year, salinity stratification as a result of
intermittent rainfall and river inflow plays a dominant role in the density
structure and circulation within the Bay. A 3-dimensional baroclinic model of
Pelorus Sound is developed and applied to the simulation of idealised pulses of
rainfall and river inflow to investigate their impact on the density structure
and circulation within Pelorus Sound, focusing on Beatrix Bay. The model shows
that the rainfall causes near-surface salinity stratification of 1-2 psu,
sufficient to introduce phase differences of c. 2 h between surface and
bottom M2 tidal currents. Following the river inflow, a surface tongue of
fresher water is seen to propagate towards the mouth of the Sound, taking
c. 4.5 days to reach Beatrix Bay, by which time tidal stirring in the
Sound has caused the fresh water to become almost well-mixed.
Keywords Pelorus Sound; Beatrix Bay; stratification; tidal
currents; hydrodynamic model
M97043
Received 21 August 1997; accepted 27 April 1998
PDF file of entire paper: medium quality (3684K); (scanned from paper original: notes about this process)
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