Non-linear model of the tides in the Gulf of Carpentaria

1981 ◽  
Vol 32 (5) ◽  
pp. 685 ◽  
Author(s):  
JA Church ◽  
AMG Fobes
Keyword(s):  
Open Boundary ◽  
Open Boundary Conditions ◽  
Kelvin Wave ◽  
Rapid Phase ◽  
North West ◽  
The North ◽  
Northern Half ◽  
Non Linear ◽  
Amphidromic Point ◽  
Phase Variations

A non-linear barotropic model was used to evaluate the tidal regime in the Gulf of Carpentaria. The model was forced by open boundary conditions specified on a line joining Wessel Islands to False Cape and a volume flow through Torres Strait estimated from tidal constants on each side of the Strait. The model gives results in agreement with the available observations and in particular predicts mixed tides in the northern half of the Gulf and diurnal tides in the south-east corner of the Gulf. The diurnal tide consists of a Kelvin wave entering the Gulf in the north-west and propagating clockwise around the Gulf with one amphidromic point. The higher frequencies of the semidiurnal tides allow the generation of a first-mqde Poincare wave and the trapping of energy in the northern half of the Gulf. Amphidromes near Mornington Island and Groote Eylandt are also predicted, as is a region of low amplitude and rapid phase variations in the centre of the Gulf.

scholarly journals The impact of sea-level rise on tidal characteristics around Australia

Ocean Science ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 147-159 ◽  
Author(s):  
Alexander Harker ◽  
J. A. Mattias Green ◽  
Michael Schindelegger ◽  
Sophie-Berenice Wilmes
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Tidal Dissipation ◽  
North West ◽  
The North ◽  
Tidal Changes ◽  
Tidal Characteristics ◽  
The Impact

Abstract. An established tidal model, validated for present-day conditions, is used to investigate the effect of large levels of sea-level rise (SLR) on tidal characteristics around Australasia. SLR is implemented through a uniform depth increase across the model domain, with a comparison between the implementation of coastal defences or allowing low-lying land to flood. The complex spatial response of the semi-diurnal M2 constituent does not appear to be linear with the imposed SLR. The most predominant features of this response are the generation of new amphidromic systems within the Gulf of Carpentaria and large-amplitude changes in the Arafura Sea, to the north of Australia, and within embayments along Australia's north-west coast. Dissipation from M2 notably decreases along north-west Australia but is enhanced around New Zealand and the island chains to the north. The diurnal constituent, K1, is found to decrease in amplitude in the Gulf of Carpentaria when flooding is allowed. Coastal flooding has a profound impact on the response of tidal amplitudes to SLR by creating local regions of increased tidal dissipation and altering the coastal topography. Our results also highlight the necessity for regional models to use correct open boundary conditions reflecting the global tidal changes in response to SLR.

scholarly journals An analytical study of <i>M</i><sub>2</sub> tidal waves in the Taiwan Strait using an extended Taylor method

Ocean Science ◽  
2018 ◽  
Vol 14 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Di Wu ◽  
Guohong Fang ◽  
Xinmei Cui ◽  
Fei Teng
Keyword(s):  
Analytical Solution ◽  
Taiwan Strait ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Kelvin Wave ◽  
Deep Basin ◽  
Tidal Waves ◽  
Taylor Method ◽  
The Cross ◽  
The Taiwan Strait

Abstract. The tides in the Taiwan Strait (TS) feature large semidiurnal lunar (M2) amplitudes. An extended Taylor method is employed in this study to provide an analytical model for the M2 tide in the TS. The strait is idealized as a rectangular basin with a uniform depth, and the Coriolis force and bottom friction are retained in the governing equations. The observed tides at the northern and southern openings are used as open boundary conditions. The obtained analytical solution, which consists of a stronger southward propagating Kelvin wave, a weaker northward propagating Kelvin wave, and two families of Poincaré modes trapped at the northern and southern openings, agrees well with the observations in the strait. The superposition of two Kelvin waves basically represents the observed tidal pattern, including an anti-nodal band in the central strait, and the cross-strait asymmetry (greater amplitudes in the west and smaller in the east) of the anti-nodal band. Inclusion of Poincaré modes further improves the model result in that the cross-strait asymmetry can be better reproduced. To explore the formation mechanism of the northward propagating wave in the TS, three experiments are carried out, including the deep basin south of the strait. The results show that the southward incident wave is reflected to form a northward wave by the abruptly deepened topography south of the strait, but the reflected wave is slightly weaker than the northward wave obtained from the above analytical solution, in which the southern open boundary condition is specified with observations. Inclusion of the forcing at the Luzon Strait strengthens the northward Kelvin wave in the TS, and the forcing is thus of some (but lesser) importance to the M2 tide in the TS.

scholarly journals An analytical study on M<sub>2</sub> tidal wave in the Taiwan Strait with the extended Taylor's method

2017 ◽  
Author(s):  
Di Wu ◽  
Guohong Fang ◽  
Xinmei Cui ◽  
Fei Teng
Keyword(s):  
Analytical Solution ◽  
Taiwan Strait ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Kelvin Wave ◽  
Deep Basin ◽  
Secondary Importance ◽  
Friction Forces ◽  
The Cross ◽  
The Taiwan Strait

Abstract. The tides in the Taiwan Strait (TS) are featured by large M2 amplitudes. The extended Taylor's method is employed in this study to provide an analytical model for the M2 tide in the TS. The strait is idealized as a rectangular basin with a uniform depth, but the Coriolis and friction forces are retained in the governing equations. The observed tides at the northern and southern openings are used as open boundary conditions. The obtained analytical solution, which consists of a stronger southward propagating Kelvin wave, a weaker northward propagating Kelvin wave, and two families of Poincaré modes trapped at the northern and southern openings, agrees well with the observations in the strait. The superposition of two Kelvin waves can basically represent the observed tidal pattern, including an anti-nodal band in the central strait, and the cross-strait asymmetry (greater amplitudes in the west and smaller in the east) of the anti-nodal band. The superposition of Poincaré modes can further improve the model result in that the cross-strait asymmetry can be better reproduced. In order to explore the formation mechanism of the northward propagating wave in the TS three experiments are carried out, including the deep basin south of the strait. The results show that the southward incident wave can be reflected to form a northward wave by the abruptly deepened topography south of the strait, but the reflected wave is slightly weaker than the northward wave obtained from above analytical solution, in which the southern open boundary condition is specified with observations. The forcing at the Luzon Strait can strengthen the northward Kelvin wave in the TS, and thus is of secondary importance to the M2 tide in the TS.

XXII.—Studies on the Scottish Marine Fauna: The Natural Faunistic Divisions of the North Sea as shown by the Quantitative Distribution of the Molluscs

1934 ◽  
Vol 57 (3) ◽  
pp. 601-616 ◽  
Author(s):  
A. C. Stephen
Keyword(s):  
North Sea ◽  
German Bight ◽  
Bottom Fauna ◽  
Marine Fauna ◽  
Quantitative Distribution ◽  
North West ◽  
The North ◽  
Northern Half ◽  
Preliminary Account ◽  
The North Sea

With the renewal of activities in Fishery Research, which took place in the lands bordering the North Sea after the War, fresh lines of investigation were introduced. Amongst others, quantitative surveys of the bottom fauna similar to those carried out by Petersen were undertaken by several countries. The southern part of the North Sea was examined by the Ministry of Agriculture and Fisheries and the results were published by Davis (2, 3). Other work undertaken in the German Bight was published by Hagmeier (6). A small survey was carried out by Petersen (8) in the North Sea off the north-west coast of Denmark. Areas to the north and west of Scotland, as well as the northern half of the North Sea, were surveyed by the Fishery Board for Scotland and a preliminary account published (11). The present paper is, in part, a summary of the results of the survey work carried out by the Fishery Board for Scotland in the northern part of the North Sea during the years 1922-25, supplemented by a subsequent survey of the intertidal areas undertaken privately; in part an analysis of the faunistic divisions of the North Sea based on the distribution of the molluscs, especially lamellibranchs, as recorded in the above papers. So far as the North Sea is concerned, the area covered by the Scottish investigations is bounded on the south approximately by latitude 56° N., and on the east and north by the 200 m. (100 fm.) contour.

Deconstructing the subtropical AMOC variability

2020 ◽  
Author(s):  
Quentin Jamet ◽  
William Dewar ◽  
Nicolas Wienders ◽  
Bruno Deremble ◽  
Sally Close ◽  
...  
Keyword(s):  
Time Scales ◽  
North Atlantic ◽  
Low Frequency ◽  
Meridional Overturning Circulation ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Intrinsic Variability ◽  
Linear Superposition ◽  
The North ◽  
Basin Scale

&lt;p&gt;Mechanisms driving the North Atlantic Meridional Overturning Circulation (AMOC) variability at low-frequency are of central interest for accurate climate predictions. However, the origin of this variability remains under debate, complicating for instance the interpretation of the observed time series provided by the RAPID-MOCHA-WBTS program. In this study, we aim at disentangling the respective contribution of the local atmospheric forcing, the signal of remote origin and the ocean intrinsic dynamics for the subtropical low-frequency AMOC variability. We analyse for this a set of four ensembles of a regional (20&lt;sup&gt;o&lt;/sup&gt;S - 55&lt;sup&gt;o&lt;/sup&gt;N), eddy-resolving (1/12&lt;sup&gt;o&lt;/sup&gt;) North Atlantic oceanic configuration, where surface forcing and open boundary conditions are alternatively permuted from fully varying (realistic) to yearly repeating signals.&lt;/p&gt;&lt;p&gt;The analysis of the four ensemble mean AMOCs reveals predominance of local, atmospherically forced signal at interannual time scales (2-10 years), while signals imposed by the boundaries imprint at decadal (10-30 years) time scales. Due to this marked time scale separation, we show that most of the subtropical AMOC forced variability can be understood as a linear superposition of these two signals. Analyzing the ensemble spread of the four ensembles, we then show that the subtropical AMOC is also characterized by an intrinsic variability, which organizes as a basin scale mode peaking at interannual time scales. This basin scale mode is found to be weakly sensitive to the surrounding forced signals, suggesting no causal relationship between the two. Its spatio-temporal pattern shares however similarities with the atmospherically forced signal, which is likely to make the attribution from a single eddy-resolving simulation, or from observations, more difficult.&lt;/p&gt;

scholarly journals Non-linear aspects of the tidal dynamics in the Sylt-Rømø Bight, south-eastern North Sea

2019 ◽  
Author(s):  
Vera Fofonova ◽  
Alexey Androsov ◽  
Lasse Sander ◽  
Ivan Kuznetsov ◽  
Felipe Amorim ◽  
...  
Keyword(s):  
Tidal Energy ◽  
Model Verification ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Residual Circulation ◽  
Tidal Dynamics ◽  
Linear Processes ◽  
Non Linear ◽  
Full Analysis ◽  
Bathymetric Map

Abstract. This study investigates the tidal dynamics in the Sylt-Rømø bight with a focus on the non-linear processes. The FESOM-C model was used as the numerical tool, which works with triangular, rectangular or mixed meshes and is equipped with a wetting/drying option. As the model's success at resolving currents largely depends on the quality of the bathymetric data, we have created a new bathymetric map for an area based on recent studies of Lister Deep, Lister Ley, and the Højer and Rømø Deep areas. This new bathymetric product made it feasible to work with high resolution grids (up to 2 m in the wetting/drying zone). As a result, we were able to study the tidal energy transformation and the role of higher harmonics in the domain in detail. For the first time, the tidal ellipses, maximum tidally-induced velocities, energy fluxes and residual circulation maps were constructed and analysed for the entire bight. Additionally, tidal asymmetry maps were introduced and constructed. The full analysis was performed on two grids with different structures and showed a convergence of the obtained results as well as fulfillment of the energy balance. A great deal of attention has been paid to the selection of open boundary conditions, model verification against available tide gauges, and recent ADCP data. The obtained results are necessary and useful benchmarks for further studies in the area, including baroclinic and sediment dynamics tasks.

scholarly journals II.—On the Cudgegong Diamond Field, New South Wales

1879 ◽  
Vol 6 (10) ◽  
pp. 444-458
Author(s):  
Norman Taylor ◽  
R. Etheridge
Keyword(s):  
New South ◽  
The West ◽  
North West ◽  
The North ◽  
North Side ◽  
South Wales ◽  
Northern Half ◽  
Southern Half ◽  
Extreme North ◽  
The Hill

The next appearance of the older lead is at the “Rocky-ridge,” where the river, after running northerly for three-quarters of a mile, along the strike of the metamorphic beds, turns abruptly to the west. This ridge is a basalt-capped hill on the north side of the river, running in a north-west direction; it is about a mile long, with a bold rocky escarpment on its west side, facing the Sandy or Cudgebeyong Creek. Some tunnels have been driven in, and shafts sunk on this hill, and tolerably rich deposits of gold were found, but never followed out.Only in the southern half of the hill have diamonds been found(all more or less spotted).The drift is remark-able for the number and size of the agates it contains.The northern half of “the ridge” is underlaid by another outlier of the before-mentioned doubtful purple conglomerate, into which some tunnels have been driven in the western escarpment.The basalt is merely a fringe here, resting against the flank of the conglomerate, in which a small quantity of nuggetty gold was obtained;and form one to two inches thickness of lignite, or carbonaceous clay, is seen between it and the bottom of the basalt. Tte basali is intersected by numerous veins of a mineral allied to kaolin. The purple con-glomerate is similar in character to that near “the flat”and contains, on some of the joint faces, smll spherical crystalline aggreations of chalybite(carbonate of iron).At the extreme north ead of “the ridge”are great quantities of ironstone and conglomerate, but, from their Carbpniferous series, which is largely developed further north.The first diamonds which found their way to Melbourne were obtained.

scholarly journals Hydrodynamic and Hydrographic Modeling of Istanbul Strait

2019 ◽  
Author(s):  
Mehmet Melih Koşucu ◽  
Mehmet Cüneyd Demirel ◽  
V.S. Ozgur Kirca ◽  
Mehmet Özger
Keyword(s):  
Mixing Layer ◽  
Open Boundary ◽  
Roughness Coefficient ◽  
Model Parameters ◽  
Temperature Profiles ◽  
Open Boundary Conditions ◽  
Pass Filter ◽  
Low Pass Filter ◽  
The North ◽  
Set Up

The aim of this study is to model hydrodynamic processes of the Istanbul Strait with its stratified flow characteristic and calibrate the most important parameters using local and global search algorithms. For that two open boundary conditions are defined, which are in the North and South part of the Strait. Observed bathymetric, hydrographic, meteorological and water level data are used to set up the Delft3D-FLOW model. First, the sensitivities of model parameters on the numerical model outputs are assessed using PEST toolbox. Then, the model is calibrated based on the objective functions focusing on the flowrates of upper and lower layers. The salinity and temperature profiles of the Strait are only used for model validation. The results show that the calibrated model outputs of Istanbul Strait are reliable and consistent with the in-situ measurements. The sensitivity analysis reveals that the Spatial Low-Pass Filter Coefficient, Horizontal Eddy Viscosity, Prandtl-Schmidt Number, Slope in log-log Spectrum and Manning Roughness Coefficient are most sensitive parameters affecting flowrate performance of the model. The agreement between observed salinity profiles and simulated model outputs is promising whereas the match between observed and simulated temperature profiles is weak showing that the model can be improved particularly for simulating the mixing layer.

Poleward boundary current off Western Australia

1983 ◽  
Vol 34 (1) ◽  
pp. 173 ◽  
Author(s):  
RORY Thompson ◽  
G Veronis
Keyword(s):  
Indian Ocean ◽  
Reverse Direction ◽  
Western Coast ◽  
Kelvin Wave ◽  
Boundary Current ◽  
North West ◽  
Leeuwin Current ◽  
The North ◽  
Great Australian Bight ◽  
A Current

The southern Indian Ocean is modelled here as a body of homogeneous water with a shelf and slope region on the eastern side. A 'Leeuwin Current' is found to be the poleward extension of a boundary current generated on the north-west slope of Australia by winter winds. Simple, approximate balances demonstrate that a current forced in one region can propagate in the direction that a Kelvin wave travels but not in the reverse direction. Thus, the Leeuwin Current can be induced by winds acting north of Cape Leeuwin but not by winds in the Great Australian Bight. This study also predicts the existence of a southward current off the western coast of Tasmania.

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