scholarly journals Relationship between Three-Dimensional Radiation Stress and Vortex-Force Representations

2021 ◽  
Vol 9 (8) ◽  
pp. 791
Author(s):  
Duoc Tan Nguyen ◽  
Ad J. H. M. Reniers ◽  
Dano Roelvink
Keyword(s):  
Three Dimensional ◽  
Ocean Model ◽  
Radiation Stress ◽  
Mean Motion ◽  
Numerical Ocean Model ◽  
The Mean ◽  
Ocean Models ◽  
Wave Induced ◽  
Mean Current

In numerical ocean models, the effect of waves on currents is usually expressed by either vortex-force or radiation stress representations. In this paper, the differences and similarities between those two representations are investigated in detail in conditions of both conservative and nonconservative waves. In addition, comparisons between different sets of equations of mean motion that apply different representations of wave-induced forcing terms are included. The comparisons are useful for selecting a suitable numerical ocean model to simulate the mean current in conditions of waves combined with currents.

On the mean motion induced by internal gravity waves

1969 ◽  
Vol 36 (4) ◽  
pp. 785-803 ◽  
Author(s):  
Francis P. Bretherton
Keyword(s):  
Gravity Waves ◽  
Wave Energy ◽  
Wave Train ◽  
Three Dimensional ◽  
Internal Gravity Waves ◽  
Wave Number ◽  
Mean Flow ◽  
Mean Velocity ◽  
Mean Motion ◽  
The Mean

A train of internal gravity waves in a stratified liquid exerts a stress on the liquid and induces changes in the mean motion of second order in the wave amplitude. In those circumstances in which the concept of a slowly varying quasi-sinusoidal wave train is consistent, the mean velocity is almost horizontal and is determined to a first approximation irrespective of the vertical forces exerted by the waves. The sum of the mean flow kinetic energy and the wave energy is then conserved. The circulation around a horizontal circuit moving with the mean velocity is increased in the presence of waves according to a simple formula. The flow pattern is obtained around two- and three-dimensional wave packets propagating into a liquid at rest and the results are generalized for any basic state of motion in which the internal Froude number is small. Momentum can be associated with a wave packet equal to the horizontal wave-number times the wave energy divided by the intrinsic frequency.

Limitation of One-Dimensional Ocean Models for Coupled Hurricane–Ocean Model Forecasts

2009 ◽  
Vol 137 (12) ◽  
pp. 4410-4419 ◽  
Author(s):  
Richard M. Yablonsky ◽  
Isaac Ginis
Keyword(s):  
North Atlantic Ocean ◽  
Three Dimensional ◽  
Ocean Model ◽  
Sea Surface ◽  
Upper Ocean ◽  
Surface Cooling ◽  
One Dimensional ◽  
Sea Surface Cooling ◽  
Ocean Models ◽  
The One

Abstract Wind stress imposed on the upper ocean by a hurricane can limit the hurricane’s intensity primarily through shear-induced mixing of the upper ocean and subsequent cooling of the sea surface. Since shear-induced mixing is a one-dimensional process, some recent studies suggest that coupling a one-dimensional ocean model to a hurricane model may be sufficient for capturing the storm-induced sea surface temperature cooling in the region providing heat energy to the hurricane. Using both a one-dimensional and a three-dimensional version of the same ocean model, it is shown here that the neglect of upwelling, which can only be captured by a three-dimensional ocean model, underestimates the storm-core sea surface cooling for hurricanes translating at <∼5 m s−1. For hurricanes translating at <2 m s−1, more than half of the storm-core sea surface cooling is neglected by the one-dimensional ocean model. Since the majority of hurricanes in the western tropical North Atlantic Ocean translate at <5 m s−1, the idealized experiments presented here suggest that one-dimensional ocean models may be inadequate for coupled hurricane–ocean model forecasting.

scholarly journals Relating Agulhas leakage to the Agulhas Current retroflection location

Ocean Science ◽  
2009 ◽  
Vol 5 (4) ◽  
pp. 511-521 ◽  
Author(s):  
E. van Sebille ◽  
C. N. Barron ◽  
A. Biastoch ◽  
P. J. van Leeuwen ◽  
F. C. Vossepoel ◽  
...  
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Atlantic Ocean ◽  
Ocean Model ◽  
Altimetry Data ◽  
Agulhas Current ◽  
Numerical Ocean Model ◽  
The Indian Ocean ◽  
The Mean ◽  
Annual Time

Abstract. The relation between the Agulhas Current retroflection location and the magnitude of Agulhas leakage, the transport of water from the Indian to the Atlantic Ocean, is investigated in a high-resolution numerical ocean model. Sudden eastward retreats of the Agulhas Current retroflection loop are linearly related to the shedding of Agulhas rings, where larger retreats generate larger rings. Using numerical Lagrangian floats a 37 year time series of the magnitude of Agulhas leakage in the model is constructed. The time series exhibits large amounts of variability, both on weekly and annual time scales. A linear relation is found between the magnitude of Agulhas leakage and the location of the Agulhas Current retroflection, both binned to three month averages. In the relation, a more westward location of the Agulhas Current retroflection corresponds to an increased transport from the Indian Ocean to the Atlantic Ocean. When this relation is used in a linear regression and applied to almost 20 years of altimetry data, it yields a best estimate of the mean magnitude of Agulhas leakage of 13.2 Sv. The early retroflection of 2000, when Agulhas leakage was probably halved, can be identified using the regression.

scholarly journals Relating Agulhas leakage to the Agulhas Current retroflection location

2009 ◽  
Vol 6 (2) ◽  
pp. 1193-1221 ◽  
Author(s):  
E. van Sebille ◽  
C. N. Barron ◽  
A. Biastoch ◽  
P. J. van Leeuwen ◽  
F. C. Vossepoel ◽  
...  
Keyword(s):  
Time Series ◽  
High Resolution ◽  
Atlantic Ocean ◽  
Ocean Model ◽  
Altimetry Data ◽  
Agulhas Current ◽  
Numerical Ocean Model ◽  
The Indian Ocean ◽  
The Mean ◽  
Annual Time

Abstract. The relation between the Agulhas Current retroflection location and the magnitude of Agulhas leakage, the transport of water from the Indian to the Atlantic Ocean, is investigated in a high-resolution numerical ocean model. Sudden eastward retreats of the Agulhas Current retroflection loop are linearly related to the shedding of Agulhas rings, where larger retreats generate larger rings. Using numerical Lagrangian floats a 37 year time series of the magnitude of Agulhas leakage in the model is constructed. The time series exhibits large amounts of variability, both on weekly and annual time scales. A linear relation is found between the magnitude of Agulhas leakage and the location of the Agulhas Current retroflection, both binned to three month averages. In the relation, a more westward location of the Agulhas Current retroflection corresponds to an increased transport from the Indian Ocean to the Atlantic Ocean. When this relation is used in a linear regression and applied to almost 20 years of altimetry data, it yields a best estimate of the mean magnitude of Agulhas leakage of 13.2 Sv. The early retroflection of 2000, when Agulhas leakage was probably halved, can be identified using the regression.

Sediment dynamics near a sandy spit with wave-induced coastal currents

2021 ◽  
Author(s):  
Jing Lu
Keyword(s):  
Dominant Role ◽  
Three Dimensional ◽  
Separated Flow ◽  
Ocean Model ◽  
Sediment Dynamics ◽  
Coastal Current ◽  
Induced Current ◽  
Dominant Wave ◽  
Induced Currents ◽  
Wave Induced

<p>    Surface gravity waves play an important role in sediment transport. Previous studies have focused on the role of bottom shear enhanced by the surface wave orbital velocity. In this study, we embedded the University of New South Wales Sediment model into the Princeton Ocean Model, which includes a three-dimensional wave module to study sediment dynamics near a sandy spit in Sanniang Bay in the South China Sea. The simulated results for the deposition rate show that wave-induced currents play a dominant role in the maintenance of the sandy spit. The spit tip was formed as a result of the separation of wave-induced coastal flow. The spit tip was shown to be a barrier to the dominant wave-induced current, and the spit base was simulated to form via sand accumulation in the shelter of the spit tip. The deposition is mainly in the low-energy region behind the tip of the spit, which can counter the erosion effect of dominant wave-induced currents. The dominant wave-induced current prompts the lateral infilling of the spit tip when both the spit tip and base are above the water surface. The sediment carried by the coastal current is deposited along the flow branch of separation and forms the spit tip, which indicates that the sediment is deposited where the longshore current changes into an offshore current. As the water depth increases along the separated flow spindle, the bottom shear stress decreases, contributing to the deposition of the spit tip.</p>

scholarly journals NEARSHORE CIRCULATIONS ON A WAVY COAST

1988 ◽  
Vol 1 (21) ◽  
pp. 193
Author(s):  
Ming-Chung Lin ◽  
Sheng-Yeh Hwang
Keyword(s):  
Differential Equation ◽  
Partial Differential Equation ◽  
Total Water ◽  
Radiation Stress ◽  
Circular Arc ◽  
Wave Characteristics ◽  
Circulation Patterns ◽  
The Mean ◽  
Set Up ◽  
Wave Induced

Nearshore circulations, produced by wave-induced radiation stress gradients, form different circulation patterns under different wave characteristics and topographical conditions. Although numerous studies of nearshore circulations, such as Bowen (1969), Miller and Barcilon (1978), Dalrymple & Lozano (1978) and so on, have been appeared in the literature, it seems that little attention is paid on the case of a non-straight shoreline. O'Rorske & Leblond (1972) have investigated the wave-induced longshore currents in a semicircular bay, while Oda (1982) has used the coordinate transformation to treat nearshore circulations on a circular-arc shaped coast. Lin and Lee (1982), introduced a small perturbation quantity of wave set-up and set-down, induced by the non-straight shoreline, into the mean total water depth to obtain a governing partial differential equation by which they investigated the nearshore circulations on a cuspate coast. In Lin and Liou (1986), a more general equation was deduced on the orthogonal curvlinear coordinate system to unify the diversities among the related theories, and moreover, to investigate the nearshore circulations on the arc-shaped coast.

scholarly journals A Divergence-Form Wave-Induced Pressure Inherent in the Extension of the Eliassen–Palm Theory to a Three-Dimensional Framework for All Waves at All Latitudes

2015 ◽  
Vol 72 (7) ◽  
pp. 2822-2849 ◽  
Author(s):  
Hidenori Aiki ◽  
Koutarou Takaya ◽  
Richard J. Greatbatch
Keyword(s):  
Three Dimensional ◽  
Conservation Equation ◽  
Divergence Form ◽  
Water Model ◽  
Gradient Term ◽  
Mean Flow ◽  
Classical Energy ◽  
Linear Waves ◽  
The Mean ◽  
Wave Induced

Classical theory concerning the Eliassen–Palm relation is extended in this study to allow for a unified treatment of midlatitude inertia–gravity waves (MIGWs), midlatitude Rossby waves (MRWs), and equatorial waves (EQWs). A conservation equation for what the authors call the impulse-bolus (IB) pseudomomentum is useful, because it is applicable to ageostrophic waves, and the associated three-dimensional flux is parallel to the direction of the group velocity of MRWs. The equation has previously been derived in an isentropic coordinate system or a shallow-water model. The authors make an explicit comparison of prognostic equations for the IB pseudomomentum vector and the classical energy-based (CE) pseudomomentum vector, assuming inviscid linear waves in a sufficiently weak mean flow, to provide a basis for the former quantity to be used in an Eulerian time-mean (EM) framework. The authors investigate what makes the three-dimensional fluxes in the IB and CE pseudomomentum equations look in different directions. It is found that the two fluxes are linked by a gauge transformation, previously unmentioned, associated with a divergence-form wave-induced pressure [Formula: see text]. The quantity [Formula: see text] vanishes for MIGWs and becomes nonzero for MRWs and EQWs, and it may be estimated using the virial theorem. Concerning the effect of waves on the mean flow, [Formula: see text] represents an additional effect in the pressure gradient term of both (the three-dimensional versions of) the transformed EM momentum equations and the merged form of the EM momentum equations, the latter of which is associated with the nonacceleration theorem.

The Effect of Aircushion Division on the Structural Loads of Large Floating Offshore Structures

2007 ◽  
Author(s):  
J. L. F. van Kessel ◽  
J. A. Pinkster
Keyword(s):  
Water Surface ◽  
Three Dimensional ◽  
Potential Method ◽  
Offshore Structures ◽  
Bending Moments ◽  
Shear Forces ◽  
Floating Structures ◽  
The Mean ◽  
Wave Induced

The effect of aircushion division on the structural loads of large floating offshore structures is described and compared with that of a rectangular barge having the same dimensions. Calculations are based on a linear three-dimensional potential method using a linear adiabatic law for the air pressures inside the cushions. The water surface within the aircushions and the mean wetted surface are modelled by panel distributions representing oscillating sources. In the presented cases the structural loads include the wave induced bending moments and shear forces along the length of the structure. Aircushions significantly influence the behaviour of large floating structures in waves and consequently reduce the bending moments. The internal loads of different configurations of aircushion supported structures are described and compared with those of a rectangular barge having the same dimensions. The significant reduction of the bending moments shows that aircushion support can be of interest for large floating structures.

Sign in / Sign up

Export Citation Format

Share Document