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New Zealand Journal of Marine and Freshwater Research abstractsM99004 Received 26 January 1999; accepted 12 July 2000
Eddy energetics in the Subtropical Front over the Chatham Rise, New ZealandSTEPHEN M. CHISWELL
National Institute of Water & Atmospheric
Abstract The Chatham Rise, which rises to a depth of
400 m immediately to the east of New Zealand, appears to constrain the
latitudinal movement of the Subtropical Front (STF). Data from current meters
moored over the Chatham Rise are used to estimate the spatial variation of mean
and turbulent kinetic energies and Reynolds stresses in and around the STF.
Mean currents over 8 months are to the east, and are stronger south of the
rise. Mean speeds at 250 m south of the rise are as high as 15 cm
s-1 compared to 4.5 cm s-1 north of the rise. In
contrast, the eddy kinetic energy is higher to the north at 8.2 J
m-3 compared to 3.3 J m-3 to the south. Short-term
current meter moorings over the crest of the rise show no coherence over length
scales of 15 km for periods less than 10 days. At 250 m depth,
Reynolds stresses are positive north of the rise, and negative south of it,
suggesting an export of momentum away from the STF. |