Oceanic circulation in the head of the Hikurangi trench, east coast, New Zealand

Heath, R. A.

doi:10.1080/00288330.1976.9515647

Cited by 23 publications

(31 citation statements)

References 11 publications

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“…The anti-clockwise flow around the South Island is known as the Southland Current. Although these currents may not be continuous, (for example, much of the EAUC does not make it into the ECC (Heath 1975)), they meet near the northern flanks of the Chatham Rise, and contribute to a generally eastward flow away from the country. These currents collectively and individually affect the climate, fisheries, and maritime environment of New Zealand.…”

Section: Regional Oceanographymentioning

confidence: 99%

Determining the internal structure of the ocean off north‐east New Zealand from surface measurements

Chiswell¹

2001

New Zealand Journal of Marine and Freshwater Research

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The assumption that variability in the circulation around the east coast of the North Island of New Zealand can be described using satellitederived sea level and temperature and two empirical modes is tested. Potential errors are quantified if such an assumption is used to derive the internal fields from surface observations. Data from 303 CTD (conductivity-temperature-depth) casts made in the region between 1994 and 1999 are first tested against a much larger XBT (expendable bathythermograph) data set to show that they are representative of the expected variability, and then used to compute the empirical modes. The empirical modes are not baroclinic modes, but probably represent the lateral meanderings and variations in strength of the East Auckland Current, together with the presence of Rossby waves in this region. If surface temperature and height can be measured precisely, 60-70% of the variance in the internal temperature and velocity perturbations can be explained with the model. The standard deviation of reconstructed internal temperature errors is about 0.6° near the surface and less with depth. The standard deviation in velocity errors is 5 cm s -1.

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Section: Regional Oceanographymentioning

confidence: 99%

Determining the internal structure of the ocean off north‐east New Zealand from surface measurements

Chiswell¹

2001

New Zealand Journal of Marine and Freshwater Research

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“…Its crest corresponds with a Subtropical Convergence Zone between Subtropic Water, which has flowed around northern New Zealand as the East Cape Current, and mixed Subantarctic Water, which has flowed around southern New Zealand as the Southland Current (Fig. 1;Burling, 1961;Heath, 1972Heath, , 1976. Although subtropical species such as flying fish live in the waters off eastern North Island, icebergs large enough to ground on the shallower parts of the Chatham Rise have often been reported off eastern South Island (Brodie and Dawson, 1971) and Antarctic erratics have been dredged from the Chatham Rise (Cullen, 1962).…”

Section: Physical Oceanographymentioning

confidence: 99%

Seismic Stratigraphy and Structure Adjacent to an Evolving Plate Boundary, Western Chatham Rise, New Zealand

Lewis¹,

Bennett²,

Herzer³

et al. 1986

Initial Reports of the Deep Sea Drilling Project

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Seismic profiles obtained from the eastern side of New Zealand, in transit to and from Site 594, illustrate the evolution of the western end of the Chatham Rise and the southern extremity of the Hikurangi Trough. They show several unconformities and several major changes in tectonic and depositional regime. The unconformities represent major changes in oceanic circulation, possibly triggered by large lowerings of sea level in the late Oligocene and late Miocene. Tectonism is exemplified by a Late Cretaceous phase of block faulting, heralding the rift from Gondwanaland, and by Plio-Pleistocene normal faulting on the northern flank of the rise antithetic to the oblique-collision plate boundary in the southern Hikurangi Trough. This active normal faulting may indicate that the northwestern corner of Chatham Rise continental crust is being dragged down with the subducting slab to the north. The depositional regime has changed from Late Cretaceous infilling of fault-angle depressions, through an early Tertiary transgression and mid-Tertiary carbonate drape, to a late Miocene-Recent sequence recording repeated glacial-interglacial events. This upper stratified unit onlaps a late Miocene erosion/phosphatization unconformity toward the crest of the rise. It is locally truncated by a slope-parallel erosion surface, with downslope buildup, which may indicate either current scour and deposition or mass movement. INTRODUCTION BackgroundIn transit between Cook Strait and Site 594, the Glomar Challenger obtained seismic profiles along approximately 900 km of ship's track. Because they are tied to borehole data and because they cross areas where tracks are sparse, the Glomar Challenger profiles provide a significant increase in our understanding of the stratigraphy of eastern New Zealand and of tectonism in continental crust adjacent to an oblique-collision plate boundary.In this paper we integrate the Glomar Challenger profiles with published syntheses, with seismic data obtained by D.S.I.R. divisions, and with compilations of oil company data on open file at the New Zealand Geological Survey. Oil company data used in this study include profiles collected by Mobil Oil Corporation, Magellan Petroleum (New Zealand) Ltd., Australian Gulf Oil company, and B.P. Shell Todd (Chatham Rise) Ltd. Geomorphological SettingThe Glomar Challenger profiles traverse the Mernoo Saddle, a depression between the continental shelf of eastern New Zealand and the east-west-trending Chatham Rise ( Fig. 1; Fig. 3, later). The saddle's sill depth is over 500 m deep, contrasting with shelf depths to east Kennett, J. P., von der Borch, C. C, et al., Init. Repts. DSDP, 90: Washington (U.S. Govt. Printing Office).

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“…Although the Wairarapa Eddy has only recently been considered important enough for it to be named, its presence has been inferred for some time, with early hydrographical analyses showing anticyclonic flow in the region (e.g., Heath 1975). The eddy was also inferred from biological considerations by Lesser (1978) who speculated that "recirculation between the East Cape Current and an anticyclonic eddy formed where it turns offshore" (i.e., the Wairarapa Eddy) could retain rock lobster larvae long enough for them to develop to the post-larval puerulus stage.…”

Section: Introductionmentioning

confidence: 99%

Circulation within the Wairarapa Eddy, New Zealand

Chiswell

2003

New Zealand Journal of Marine and Freshwater Research

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The Wairarapa Eddy appears as a permanent anticyclonic eddy situated off the east coast of the North Island, New Zealand. In April 2001 a spatial survey of the eddy was made on a ship equipped with an Acoustic Doppler Current Profiler (ADCP). The absolute circulation at 100 m was estimated by objective mapping of the ADCP-derived velocities to produce a velocity field that has enforced non-divergence. Assuming that enforcing non-divergence produces the best estimate of the geostrophic flow, this velocity field can be used as a "level of known motion" to reference geostrophic velocities at other depths. In particular, it can be used to estimate the velocity at 2000 dbar, which is otherwise used in this region as a level of no motion. The resulting flow at 2000 dbar has a mean speed of 0.07 m s -1 , and appears to be well correlated with the surface flow.

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Oceanic circulation in the head of the Hikurangi trench, east coast, New Zealand

Cited by 23 publications

References 11 publications

Determining the internal structure of the ocean off north‐east New Zealand from surface measurements

Determining the internal structure of the ocean off north‐east New Zealand from surface measurements

Seismic Stratigraphy and Structure Adjacent to an Evolving Plate Boundary, Western Chatham Rise, New Zealand

Circulation within the Wairarapa Eddy, New Zealand

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