Large-scale influence of the New Zealand seafloor topography on western boundary currents of the South Pacific Ocean.

1985 ◽  
Vol 36 (1) ◽  
pp. 1 ◽  
Author(s):  
RA Heath
Keyword(s):  
New Zealand ◽  
West Coast ◽  
East Coast ◽  
South Pacific ◽  
Surface Flow ◽  
Current Speed ◽  
Western Boundary ◽  
East Australian Current ◽  
South Pacific Ocean ◽  
Tasman Sea

The extensive New Zealand submarine platform lying approximately 1600 km east of Australia has a strong influence on the South Pacific circulation. Together with the Kermadec Ridge, it is the western boundary of the deep South Pacific Ocean with an associated deep western boundary current. Although New Zealand probably influences where the East Australian Current separates from the east Australian coast, at the latitude of northernmost New Zealand, the sloping seafloor on the New Zealand west coast does allow for a meridional flow there. However, the decrease in current speed with depth does decrease the influence of the bottom topography. The net result is that there is both an intensification of the zonal flow across the Tasman Sea at the latitude of northernmost New Zealand, the speed of which is enhanced by the flow over the extensive ridge system, and a general eastwards flow in the Tasman Sea over the latitudinal range of New Zealand, which feeds meridional flows on the New Zealand west coast. It is suggested that the general west to east flow past New Zealand restricts the westward propagation of second- and higher-order baroclinic Rossby waves with the result that, whereas the East Australian Current has rapid near-surface flow which decreases rapidly with depth in the upper 500 m, the surface flow on the east coast of New Zealand is less rapid and decreases more uniformly with depth. One possible consequence of the current speed change with depth is that the flow and eddies on the New Zealand east coast appear to be influenced by the bathymetry whereas the East Australian Current eddies are more a primary component of the current linked to instability in the current system.

Geopotential Topographies and Associated Circulation in the Western South Pacific Ocean

1962 ◽  
Vol 13 (2) ◽  
pp. 89 ◽  
Author(s):  
K Wyrtki
Keyword(s):  
New Zealand ◽  
Pacific Ocean ◽  
Solomon Islands ◽  
South Pacific ◽  
South Pacific Ocean ◽  
Surface Circulation ◽  
Tasman Sea ◽  
Water Mass Analysis ◽  
Subsurface Layers ◽  
Induced Currents

Geopotential topographies of the surface and several subsurface depths are drawn from observations on three cruises of H.M.A.S. Gascoyne in the waters of the western South Pacific Ocean in 1960 and 1961. The associated circulation is discussed. Surface circulation is found to be in agreement with the topographies only in the major current branches, while wind-induced currents do not show in the topographies. The inflow into the region occurs from the east between 25� S. and the Solomon Islands. It is stronger in subsurface layers than at the surface. A comparison with five cruises made by the Institut Franpais d'Oceanie in Noumea into the region between Kew Caledonia and the Solomons shows a permanent inflow in layers between 100 and 700 m, while the geostrophic circulation at the surface is very variable. The outflow from the region is effected by a current in the Tasman Sea between 30� and 36� S. flowing east and leaving the region north of New Zealand. Between Tasmania and New Zealand an outflow to the south occurs, reaching to 1200 m depth. The East Australian Current continues as an eddy system as far south as Tasmania. The calculated current pattern agrees in all parts with the circulation as derived from water mass analysis.

scholarly journals The East Australian Current and Property Transport at 27°S from 2012 to 2013

2016 ◽  
Vol 46 (3) ◽  
pp. 993-1008 ◽  
Author(s):  
Bernadette M. Sloyan ◽  
Ken R. Ridgway ◽  
Rebecca Cowley
Keyword(s):  
Western Boundary ◽  
East Australian Current ◽  
Boundary Current ◽  
Orthogonal Function ◽  
South Pacific Ocean ◽  
Tasman Sea ◽  
Mode 2 ◽  
Complex Empirical Orthogonal Function ◽  
Velocity Anomalies ◽  
The Mean

AbstractThe East Australian Current (EAC) is the complex and highly energetic poleward western boundary current of the South Pacific Ocean. A full-depth current meter and property (temperature and salinity) mooring array was deployed from the continental shelf to the abyssal waters off Brisbane Australia (27°S) for 18 months from April 2012 to August 2013. The EAC mooring array is an essential component of the Australian Integrated Marine Observing System (IMOS). During this period the EAC was coherent with an eddy kinetic to mean kinetic energy ratio of less than 1. The 18-month, mean, poleward-only mass transport above 2000 m is 22.1 ± 7.5 Sverdrups (Sv; 1 Sv ≡ 106 m3 s−1). The mean, poleward-only heat transport and flow-weighted temperature above 2000 m are −1.35 ± 0.42 PW and 15.33°C, respectively. A difference in the poleward-only and net poleward mass and heat transports above 2000 m of 6.3 Sv and 0.24 PW reflects the presence of an equatorward EAC retroflection at the eastern (offshore) end of the mooring array. A complex empirical orthogonal function (EOF) analysis of the along-slope velocity anomalies finds that the first two modes explain 72.1% of the velocity variance. Mode 1 is dominant at periods of approximately 60 days, and mode 2 is dominant at periods of 120 days. These dominant periods agree with previous studies in the Tasman Sea south of 27°S and suggest that variability of the EAC in the Tasman Sea may be linked to variability north of 27°S.

scholarly journals Subduction of South Pacific Tropical Water and Its Equatorward Pathways as Shown by a Simulated Passive Tracer*

2013 ◽  
Vol 43 (8) ◽  
pp. 1551-1565 ◽  
Author(s):  
Tangdong Qu ◽  
Shan Gao ◽  
Rana A. Fine
Keyword(s):  
South Pacific ◽  
Equatorial Region ◽  
Equatorial Pacific ◽  
Western Boundary ◽  
Passive Tracer ◽  
Tropical Water ◽  
South Pacific Ocean ◽  
Equal Importance ◽  
Equatorial Thermocline ◽  
South Pacific Tropical Water

Abstract This study investigates the subduction of South Pacific Tropical Water (SPTW) and its equatorward pathways using a simulated passive tracer of the consortium Estimating the Circulation & Climate of the Ocean (ECCO). The results show that approximately 5.8 Sv (1 Sv ≡ 106 m3 s−1) of the SPTW is formed in the subtropical South Pacific Ocean within the density range between 24.0 and 25.0 kg m−3, of which about 87% is due to vertical pumping and 13% is due to lateral induction, comparing reasonably well with estimates from climatological data. Once subducted, most SPTW spreads in the subtropical South Pacific. Because of the presence of mixing, some portion of the water is transformed, and its tracer-weighted density steadily increases from an initial value of 24.4 to nearly 25.0 kg m−3 after 13 years of integration. Approximately 42% of the water makes its way into the equatorial Pacific, either through the western boundary or interior pathway. The two equatorward pathways are essentially of equal importance. A large (~70%) portion of the SPTW entering the equatorial region resurfaces in the central equatorial Pacific. The potential impacts of the resurfacing SPTW on the equatorial thermocline and surface stratification are discussed.

LUCERNE IN THE WELLINGTON, TARANAKI, AND EAST COAST DISTRICTS

1936 ◽  
pp. 92-95
Author(s):  
A.G. Elliott ◽  
T.W. Lonsdale
Keyword(s):  
New Zealand ◽  
West Coast ◽  
East Coast ◽  
General Trend ◽  
Present Position ◽  
Department Of Agriculture ◽  
Forage Crop ◽  
High Rainfall ◽  
The North ◽  
Subsequent Discussion

IN two papers read by officers of the Department of Agriculture at the 1936 conference of the New Zealand Grassland Association, the growing of lucernc as a forage crop in districts of relatively high rainfall was dealt with. The area covered by the papers included the Manawatu and west coast from Paraparaumu to the Patea River(I) and Taranaki(n). During the subsequent discussion on these and other papers the present position and general trend in regard to lucernegrowing in the Wairarapa, Eiawke's Eay, and Poverty Bay districts were also touched on. It is the intention here. to review briefly some of the more important points in regard to the cultivation of lucerne in the southern portion of the North Island as discussed at the conference.

scholarly journals Preface: The Oligotrophy to the UlTra-oligotrophy PACific Experiment (OUTPACE cruise, 18 February to 3 April 2015)

2017 ◽  
Vol 14 (13) ◽  
pp. 3207-3220 ◽  
Author(s):  
Thierry Moutin ◽  
Andrea Michelangelo Doglioli ◽  
Alain de Verneil ◽  
Sophie Bonnet
Keyword(s):  
Biological Diversity ◽  
New Caledonia ◽  
Austral Summer ◽  
South Pacific ◽  
Adaptive Strategy ◽  
French Polynesia ◽  
Biogenic Elements ◽  
General Context ◽  
Western Boundary ◽  
South Pacific Ocean

Abstract. The overall goal of OUTPACE (Oligotrophy to UlTra-oligotrophy PACific Experiment) was to obtain a successful representation of the interactions between planktonic organisms and the cycle of biogenic elements in the western tropical South Pacific Ocean across trophic and N2 fixation gradients. Within the context of climate change, it is necessary to better quantify the ability of the oligotrophic ocean to sequester carbon through biological processes. OUTPACE was organized around three main objectives, which were (1) to perform a zonal characterization of the biogeochemistry and biological diversity of the western tropical South Pacific during austral summer conditions, (2) to study the production and fate of organic matter (including carbon export) in three contrasting trophic regimes (increasing oligotrophy) with a particular emphasis on the role of dinitrogen fixation, and (3) to obtain a representation of the main biogeochemical fluxes and dynamics of the planktonic trophic network. The international OUTPACE cruise took place between 18 February and 3 April 2015 aboard the RV L'Atalante and involved 60 scientists (30 onboard). The west–east transect covered  ∼  4000 km from the western part of the Melanesian archipelago (New Caledonia) to the western boundary of the South Pacific gyre (French Polynesia). Following an adaptive strategy, the transect initially designed along the 19° S parallel was adapted along-route to incorporate information coming from satellite measurements of sea surface temperature, chlorophyll a concentration, currents, and diazotroph quantification. After providing a general context and describing previous work done in this area, this introductory paper elucidates the objectives of OUTPACE, the implementation plan of the cruise and water mass and climatological characteristics and concludes with a general overview of the other papers that will be published in this special issue.

scholarly journals Ocean Sensors Record Rare Triple Tsunami near New Zealand

Eos ◽  
2021 ◽  
Vol 102 ◽  
Author(s):  
Katherine Kornei
Keyword(s):  
New Zealand ◽  
Pacific Ocean ◽  
South Pacific ◽  
The South ◽  
South Pacific Ocean

A new suite of DART buoys in the South Pacific Ocean spotted waves set in motion by three tsunamigenic earthquakes that occurred within hours of one another.

scholarly journals The Role of the New Zealand Plateau in the Tasman Sea Circulation and Separation of the East Australian Current

2018 ◽  
Vol 123 (2) ◽  
pp. 1457-1470 ◽  
Author(s):  
Christopher Y. S. Bull ◽  
Andrew E. Kiss ◽  
Erik van Sebille ◽  
Nicolas C. Jourdain ◽  
Matthew H. England
Keyword(s):  
New Zealand ◽  
East Australian Current ◽  
Tasman Sea

scholarly journals Planktic Foraminifera-Based Sea Surface Temperature Estimates and Late Quaternary Oceanography off New Zealand's West Coast

2021 ◽  
Author(s):  
◽  
Andrew Peter Kolodziej
Keyword(s):  
New Zealand ◽  
Surface Water ◽  
West Coast ◽  
Mass Movement ◽  
Sea Surface ◽  
Temperate Species ◽  
Tasman Sea ◽  
Modern Analogue ◽  
Neogloboquadrina Dutertrei ◽  
Glacial Periods

<p>Planktic foraminiferal assemblages were used to investigate the paleoceanography of the Eastern Tasman Sea over the last 480 kyrs (Marine Isotope Stages 12-1). One hundred and sixty-two faunas (96 picked and identified as part of this project (MIS 12-6) added to 66 census counts from Dr. M. Crundwell (MIS 6-1)) have been assembled from Marion Dufresne piston core MD06-2986 (~43˚ S. off New Zealand‟s west coast, 1477 m water depth). Faunal changes through the last five glacial-interglacial cycles are used to track surface water mass movement. Glacial periods are dominated by the eutrophic species Globigerina bulloides, with significant contributions from the temperate species Globoconella inflata. Temperate species Neogloboquadrina incompta and Gc. inflata dominate interglacials, with the former dominating the warmer parts and the latter dominating the cooler parts of the interglacials. Modern Analogue Technique (MAT) and an Artificial Neural Network (ANN) were used to estimate past sea surface temperatures (SST) based on the foraminiferal census counts data (23 species, ~46,000 specimens). SSTs show that MIS 12 was the longest, sustained cold period, while the coldest temperature was recorded in MIS 5d (~8º C). Interglacials MIS 11 and 5e are the two warmest stages of the record, with SSTs reaching ~18.5º C, about ~2º C warmer than present day. We find that contrary to either the western Tasman Sea or offshore eastern New Zealand, the eastern Tasman Sea has been fairly isolated from any major influx of subpolar or subtropical species carried in with surface water from either high or low latitude sources. Subtropical taxa abundance (Globigerinoides ruber, Neogloboquadrina dutertrei (D), Globigerinoides sacculifer, Globigerinella aequilateralis, Sphaeroidinellopsis dehiscens, Truncorotalia truncatulinoides (D), Beella digitata) is low (average ~0.6%) and only prominent during peak interglacials. Subantarctic taxa abundance (Neogloboquadrina pachyderma, Neogloboquadrina dutertrei (S)) is low (average ~5.1%), but significant, particularly in glacial periods. Comparison of faunal and SSTANN data along with ratios of Nq. pachyderma:Nq. incompta (previously referred to as coiling ratios of Nq. pachyderma) and absolute abundance of planktic productivity (a productivity proxy) suggest that the STF migrated northwards towards the site in all glacial periods, and may have moved over the site in MIS 12 and possibly MIS 5d. A latitudinal SSTANN 25 comparison between offshore eastern and western New Zealand reveals that MD06-2986 (~43º S) is most similar (~0.5º C) to ODP Site 1125 (~42º S). On the contrary, ODP Site 1119 (44º S) is ~5º C cooler than MD06-2986. This comparison highlights the significant changes in surface water masses off eastern New Zealand that exist in such a short span of latitude because of the influence of a complex submarine topography.</p>

Optical properties of ocean waters in the vicinity of the Chatham Rise, South Pacific Ocean

1998 ◽  
Vol 49 (1) ◽  
pp. 1 ◽  
Author(s):  
David Shooter ◽  
Robert J. Davies-Colley ◽  
John T. O. Kirk ◽  
Anne-Maree Schwarz
Keyword(s):  
Optical Properties ◽  
Chlorophyll Fluorescence ◽  
New Zealand ◽  
Pacific Ocean ◽  
Attenuation Coefficient ◽  
Coastal Waters ◽  
South Pacific ◽  
Spectral Irradiance ◽  
Convergence Zone ◽  
South Pacific Ocean

Apparent optical properties of the water at 21 ocean stations in the South Pacific, east of New Zealand in the vicinity of the Chatham Rise, have been studied. Spectral irradiance attenuation and reflectance, and PAR irradiance attenuation, were measured in Sub-tropical and Sub-antarctic water masses, in the Sub-tropical Convergence zone between them, and in coastal waters. The waters studied are considered to be predominantly Jerlov optical types II and III. Anomalous features at wavelengths above 590 nm in the spectra of reflectance and of the vertical attenuation coefficient for upward irradiance were attributed predominantly to Raman emission with a contribution from chlorophyll fluorescence at longer wavelengths.

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