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Internal tide dissipation, mixing, and vertical nitrate flux at the shelf edge of NE New Zealand

Internal tide dissipation, mixing, and vertical nitrate flux at the shelf edge of NE New Zealand
Internal tide dissipation, mixing, and vertical nitrate flux at the shelf edge of NE New Zealand
An internal tide on the NE shelf of New Zealand was observed with a combination of moored temperature loggers and current meters and vertical profiling with a microstructure probe. Internal tide energy flux across the shelf edge was calculated to be 400 W m -1, with considerable variability driven by the passage of a storm through the region. Energy associated with the internal tide was significantly greater than the energy of the barotropic tide or of inertial shear. Dissipation of the internal tide calculated from the energy loss between two of the moorings was estimated to be 15 10 mW m -2. The associated vertical eddy diffusivity was (4 3) 10 -4 m 2 s -1. The microstructure observations indicated internal tide-driven vertical diffusivities at the nitracline of 7 10 -4 m 2 s -1. The observations of vertical eddy diffusivities are combined with measurements of the vertical nitrate gradient to suggest that mixing driven by the internal tide is the dominant mechanism for driving diapycnal nutrient supply during summer. The calculated flux of about 12 mmol N m -2 d -1 into the photic zone is suggested to drive significant new subsurface production throughout the summer, amounting to a possible contribution to annual new production on the shelf of 100 g C m -2.
INTERNAL TIDES, NEW ZEALAND WATERS, NITRATE, SHELF DYNAMICS
0148-0227
14069-14081
Sharples, J.
ec7edc0d-5f09-4b12-a832-0c7bf6a4b3ff
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Abraham, E.R.
20e2a30b-90b9-4614-ac5b-d4cbc9021b5e
Sharples, J.
ec7edc0d-5f09-4b12-a832-0c7bf6a4b3ff
Moore, C.M.
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Abraham, E.R.
20e2a30b-90b9-4614-ac5b-d4cbc9021b5e

Sharples, J., Moore, C.M. and Abraham, E.R. (2001) Internal tide dissipation, mixing, and vertical nitrate flux at the shelf edge of NE New Zealand. Journal of Geophysical Research, 106 (C7), 14069-14081.

Record type: Article

Abstract

An internal tide on the NE shelf of New Zealand was observed with a combination of moored temperature loggers and current meters and vertical profiling with a microstructure probe. Internal tide energy flux across the shelf edge was calculated to be 400 W m -1, with considerable variability driven by the passage of a storm through the region. Energy associated with the internal tide was significantly greater than the energy of the barotropic tide or of inertial shear. Dissipation of the internal tide calculated from the energy loss between two of the moorings was estimated to be 15 10 mW m -2. The associated vertical eddy diffusivity was (4 3) 10 -4 m 2 s -1. The microstructure observations indicated internal tide-driven vertical diffusivities at the nitracline of 7 10 -4 m 2 s -1. The observations of vertical eddy diffusivities are combined with measurements of the vertical nitrate gradient to suggest that mixing driven by the internal tide is the dominant mechanism for driving diapycnal nutrient supply during summer. The calculated flux of about 12 mmol N m -2 d -1 into the photic zone is suggested to drive significant new subsurface production throughout the summer, amounting to a possible contribution to annual new production on the shelf of 100 g C m -2.

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More information

Published date: 2001
Keywords: INTERNAL TIDES, NEW ZEALAND WATERS, NITRATE, SHELF DYNAMICS

Identifiers

Local EPrints ID: 7936
URI: http://eprints.soton.ac.uk/id/eprint/7936
ISSN: 0148-0227
PURE UUID: 5794c415-3544-456e-ac58-40e9ad5dc73f
ORCID for C.M. Moore: ORCID iD orcid.org/0000-0002-9541-6046

Catalogue record

Date deposited: 10 Aug 2004
Last modified: 09 Jan 2022 03:01

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Contributors

Author: J. Sharples
Author: C.M. Moore ORCID iD
Author: E.R. Abraham

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