Shelfbreak upwelling induced by alongshore currents: analytical and numerical results

2011 ◽  
Vol 686 ◽  
pp. 239-249 ◽  
Author(s):  
Robert N. Miller ◽  
Ricardo P. Matano ◽  
Elbio D. Palma
Keyword(s):  
Shallow Water Equations ◽  
Numerical Experiments ◽  
Coastal Upwelling ◽  
Quantitative Agreement ◽  
Numerical Results ◽  
Ekman Transport ◽  
Ecological Features ◽  
Coastal Trapped Waves ◽  
Steady Solutions ◽  
Arrested Topographic Wave

AbstractAlongshore flow in the direction of propagation of coastal trapped waves can result in upwelling at the shelfbreak. The intensity of this upwelling can be comparable in magnitude to wind-driven coastal upwelling, with its associated ecological features. Recent numerical experiments by Matano & Palma indicate that this upwelling results from convergence of Ekman transport at the shelfbreak. The mechanism for this phenomenon can be understood in terms of steady solutions to the shallow water equations in the presence of Coriolis force and bottom drag. Matano & Palma interpreted their numerical results in terms of the arrested topographic wave, but did not present direct comparisons. Here we present a family of analytical solutions to the equations of the arrested topographic wave that shows striking quantitative agreement with earlier numerical results.

RECENT DEVELOPMENTS IN THE NUMERICAL SIMULATION OF SHALLOW WATER EQUATIONS II: TEMPORAL DISCRETIZATION

1994 ◽  
Vol 04 (04) ◽  
pp. 533-556 ◽  
Author(s):  
V. AGOSHKOV ◽  
E. OVCHINNIKOV ◽  
A. QUARTERONI ◽  
F. SALERI
Keyword(s):  
Numerical Simulation ◽  
Finite Element ◽  
Finite Difference ◽  
Shallow Water ◽  
Shallow Water Equations ◽  
Numerical Results ◽  
Finite Difference Approximation ◽  
Difference Approximation ◽  
Recent Developments ◽  
Numerical Approaches

This paper deals with time-advancing schemes for shallow water equations. We review some of the existing numerical approaches, propose new schemes and investigate their stability. We present numerical results obtained using the time-advancing schemes proposed, with finite element and finite difference approximation in space variables.

scholarly journals SEASONAL PATTERN OF WIND INDUCED UPWELLING OVER JAVA-BALI SEA WATERS AND SURROUNDING AREA

2010 ◽  
Vol 5 (1) ◽  
Author(s):  
Siswanto ◽  
Suratno
Keyword(s):  
Wind Stress ◽  
Coastal Upwelling ◽  
Sea Water ◽  
Mixed Layer Depth ◽  
Surface Wind ◽  
Ekman Transport ◽  
Monsoon Circulation ◽  
Wide Field ◽  
Surrounding Area ◽  
Noaa Avhrr

The influence of monsoonal wind to coastal upwelling mechanism which is generated by Ekman transport was studied here by analyzing wind stress curl (WSC) distribution over Java-Bali Sea waters and its surrounding area. Surface wind data were used as input data to calculate curl of wind stress in barotropic model. Confirmation with Corioli effect in the Southern Hemisphere, it could be known that negative curl value has relation with vertical motion of sea water as resulted by Ekman transport. Result of analysis showed that negative curl near coast over Java Sea which is stretching to Lombok Sea occurred in December to April when westerly wind of the North West Monsoon actives. It can be guidance and related with season of coastal upwelling in the region. Reversal condition, the occurrance of coastal upwelling in the south coast of JAva island related with the negative value of WSC that occurs since easterlies wind take place in May to August as a part of South East Monsoon episode. Generally, upwelling occurrance in the field of study is a response to the Monsoon circulation. This study with related data such as sea surface temperature, chlorophyll concetration and mixed layer depth that derived from satellite imaging data National Oceanic and Atmospheric Administration Advanced Very High Resolution Radiometer (NOAA-AVHRR), Aqua/Modis and sea viewing Wide Field-of-view Sensor(Sea WiFS) shows as magnificent confirmation pattern. So applying WSC to recoqnize upwelling zone is alternatively way as climatic approach to maps potential fertilizing of sea water in maritime-continent Indonesia. Key words: coastal upwelling, Ekman transport, Java-Bali Sea, Monsoon circulation, upwelling.

scholarly journals Seasonal variability of the Ekman transport and pumping in the upwelling system off central-northern Chile (∼  30° S) based on a high-resolution atmospheric regional model (WRF)

Ocean Science ◽  
2016 ◽  
Vol 12 (5) ◽  
pp. 1049-1065 ◽  
Author(s):  
Luis Bravo ◽  
Marcel Ramos ◽  
Orlando Astudillo ◽  
Boris Dewitte ◽  
Katerina Goubanova
Keyword(s):  
High Resolution ◽  
Wind Stress ◽  
Seasonal Variability ◽  
Coastal Upwelling ◽  
Ekman Transport ◽  
Northern Chile ◽  
Ekman Pumping ◽  
Relative Contribution ◽  
Alongshore Wind Stress ◽  
Alongshore Wind

Abstract. Two physical mechanisms can contribute to coastal upwelling in eastern boundary current systems: offshore Ekman transport due to the predominant alongshore wind stress and Ekman pumping due to the cyclonic wind stress curl, mainly caused by the abrupt decrease in wind stress (drop-off) in a cross-shore band of 100 km. This wind drop-off is thought to be an ubiquitous feature in coastal upwelling systems and to regulate the relative contribution of both mechanisms. It has been poorly studied along the central-northern Chile region because of the lack in wind measurements along the shoreline and of the relatively low resolution of the available atmospheric reanalysis. Here, the seasonal variability in Ekman transport, Ekman pumping and their relative contribution to total upwelling along the central-northern Chile region (∼  30° S) is evaluated from a high-resolution atmospheric model simulation. As a first step, the simulation is validated from satellite observations, which indicates a realistic representation of the spatial and temporal variability of the wind along the coast by the model. The model outputs are then used to document the fine-scale structures in the wind stress and wind curl in relation to the topographic features along the coast (headlands and embayments). Both wind stress and wind curl had a clear seasonal variability with annual and semiannual components. Alongshore wind stress maximum peak occurred in spring, second increase was in fall and minimum in winter. When a threshold of −3  ×  10−5 s−1 for the across-shore gradient of alongshore wind was considered to define the region from which the winds decrease toward the coast, the wind drop-off length scale varied between 8 and 45 km. The relative contribution of the coastal divergence and Ekman pumping to the vertical transport along the coast, considering the estimated wind drop-off length, indicated meridional alternation between both mechanisms, modulated by orography and the intricate coastline. Roughly, coastal divergence predominated in areas with low orography and headlands. Ekman pumping was higher in regions with high orography and the presence of embayments along the coast. In the study region, the vertical transport induced by coastal divergence and Ekman pumping represented 60 and 40 % of the total upwelling transport, respectively. The potential role of Ekman pumping on the spatial structure of sea surface temperature is also discussed.

scholarly journals Parallel in Time Algorithms for Nonlinear Iterative Methods

2018 ◽  
Vol 63 ◽  
pp. 248-257 ◽  
Author(s):  
Mustafa Gaja ◽  
Olga Gorynina
Keyword(s):  
Boundary Condition ◽  
Structural Analysis ◽  
Iterative Methods ◽  
Numerical Experiments ◽  
Numerical Results ◽  
Contact Boundary ◽  
Nonlinear Structural Analysis ◽  
Nonlinear Structural

In this paper we investigate the feasibility of applying the Parareal algorithm [5, 6] for quasi-static nonlinear structural analysis problems. We describe how this proposal has been realized and present some preliminary numerical results of applying this algorithm to a beam undergoing nonlinear deflection with a contact boundary condition. Further numerical experiments are needed to provide an evidence for the effciency of the method.

The El Nino-Southern Oscillation in south-eastern Australian waters

1991 ◽  
Vol 42 (3) ◽  
pp. 263 ◽  
Author(s):  
WW Hsieh ◽  
BV Hamon
Keyword(s):  
Sea Level ◽  
Coastal Upwelling ◽  
Southern Oscillation ◽  
Geostrophic Wind ◽  
Air Pressure ◽  
Ekman Transport ◽  
Hydrographic Data ◽  
South Eastern ◽  
Eastern Australia ◽  
South Eastern Australia

Using four decades of hydrographic data collected off the coast near Sydney, New South Wales, and sea-level data at Sydney, we studied the interannual variability in south-eastern Australian shelf waters. The first two empirical orthogonal function (EOF) modes of the band-pass-filtered 50-m-depth hydrographic data (temperature, T; salinity, S; nitrate, N; inorganic phosphate, P; and oxygen, O) and the sea level (SL) and adjusted sea level (ASL) data accounted respectively for 51 and 27% of the total variance. Both modes were significantly correlated with the Southern Oscillation Index (SOI). The first mode, with T, S, O and ASL varying in opposition to N and P, represented the internal or baroclinic response, associated with vertical displacements of the isopycnals. The second mode, with large in-phase fluctuations in SL and ASL but small changes in the hydrographic variables, represented mainly the external or barotropic response during the El Niiio-Southern Oscillation (ENSO). Three-year composites centred around seven ENSO warm episodes revealed that T, S, O and ASL were generally low and N, P, SL and SO1 were high in the year before each ENSO warm episode, but the former group rose while the latter group dropped in the year of the warm episode. The changes in the hydrographic variables at 50 m depth were consistent with relatively shallow isopycnals in the year before the ENSO warm episode, followed by a deepening of the isopycnals during the warm episode. Estimates of this downward displacement of isopycnals, as determined from T, N, P and O, were in the range 7-10 m. The geostrophic wind arising from the pressure fluctuations during ENSO is proposed as a probable cause for the vertical displacement of the isopycnals. In the year before the warm episode, the low air pressure over Australia would produce a clockwise geostrophic wind around south-eastern Australia, generating offshore Ekman transport and coastal upwelling. During the warm episode, air pressure over Australia rises, the geostrophic wind reverses, and downward movement of the isopycnals would occur off south-eastern Australia.

The Elastohydrodynamic Problem Expressed in Terms of Extended Variational Formulation

1986 ◽  
Vol 108 (4) ◽  
pp. 557-564 ◽  
Author(s):  
Antonio Strozzi
Keyword(s):  
Convergence Rate ◽  
Variational Formulation ◽  
Numerical Experiments ◽  
Numerical Results ◽  
Lubricated Contacts ◽  
Relaxation Scheme

The elastohydrodynamic problem is revisited in terms of an extended variational formulation, where the corresponding functional exhibits minimum properties in the solution neighborhood. Such features are exploited in the development of a relaxation-type solver. The numerical results indicate that the convergence rate of the proposed relaxation scheme becomes increasingly poor as the solution of the elastohydrodynamic problem is approached. A polyalgorithm based on a combination between relaxation-type and Newton-type schemes is proposed. The numerical experiments referred to various sealing profiles of increasing foundation compliance show that the proposed procedure is particularly advantageous in the case of soft lubricated contacts.

Numerical Experiments on Scattering of Coastal-Trapped Waves by Topography and Bays

2005 ◽  
Vol 14 (3) ◽  
pp. 441-458 ◽  
Author(s):  
Yosuke Igeta ◽  
Yujiro Kitade ◽  
Masaji Matsuyama
Keyword(s):  
Numerical Experiments ◽  
Trapped Waves ◽  
Coastal Trapped Waves

Solving Two-Mode Shallow Water Equations Using Finite Volume Methods

2014 ◽  
Vol 16 (5) ◽  
pp. 1323-1354 ◽  
Author(s):  
Manuel Jesús Castro Diaz ◽  
Yuanzhen Cheng ◽  
Alina Chertock ◽  
Alexander Kurganov
Keyword(s):  
Shallow Water ◽  
Numerical Method ◽  
Shallow Water Equations ◽  
Numerical Experiments ◽  
Operator Splitting ◽  
Finite Volume Methods ◽  
Splitting Methods ◽  
Upwind Scheme ◽  
Operator Splitting Methods ◽  
Numerical Approaches

AbstractIn this paper, we develop and study numerical methods for the two-mode shallow water equations recently proposed in [S. STECHMANN, A. MAJDA, and B. KHOUIDER, Theor. Comput. Fluid Dynamics, 22 (2008), pp. 407-432]. Designing a reliable numerical method for this system is a challenging task due to its conditional hyperbolicity and the presence of nonconservative terms. We present several numerical approaches—two operator splitting methods (based on either Roe-type upwind or central-upwind scheme), a central-upwind scheme and a path-conservative central-upwind scheme—and test their performance in a number of numerical experiments. The obtained results demonstrate that a careful numerical treatment of nonconservative terms is crucial for designing a robust and highly accurate numerical method.

GENERATION OF BRIGHT MATTER-WAVE SOLITON PATTERNS IN MIXTURES OF BOSE–EINSTEIN CONDENSATES WITH CUBIC AND QUINTIC NONLINEARITIES

2014 ◽  
Vol 28 (04) ◽  
pp. 1450003 ◽  
Author(s):  
DIDIER BELOBO BELOBO ◽  
GERMAIN HUBERT BEN-BOLIE ◽  
TIMOLÉON CRÉPIN KOFANÉ
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Linear Stability Analysis ◽  
Numerical Experiments ◽  
Modulational Instability ◽  
Numerical Results ◽  
Matter Wave ◽  
Bright Solitons ◽  
Bose Einstein

The modulational instability (MI) of binary condensates with cubic-quintic nonlinearities is investigated. Using a linear stability analysis, a gain of instability is derived then, effects of the quintic nonlinearities on the instability gain are identified. To be precise, attractive intraspecie quintic nonlinearities enhance the instability, while repulsive quintic intraspecie nonlinearities soften the instability. Besides, small attractive and large repulsive quintic inter-species nonlinearities increase the instability. Numerical experiments quite well corroborate the analytical predictions. Further numerical results show effects of the cubic and the quintic nonlinearities on the propagation of trains of bright solitons generated.

Selection of a Constitutive Model Used for Prediction of Behaviour of Ring Material Expanded by Pulse Electromagnetic Field

2009 ◽  
Vol 147-149 ◽  
pp. 444-449
Author(s):  
Robert Panowicz ◽  
Jacek Janiszewski
Keyword(s):  
Constitutive Model ◽  
Dynamic Behaviour ◽  
Constitutive Models ◽  
Quantitative Agreement ◽  
Numerical Results ◽  
Ring Test ◽  
Pulse Electromagnetic Field ◽  
Analogous Data ◽  
Ring Material ◽  
Selection Of

Selection of a constitutive model from commonly used ones, which in the best way describes dynamic behaviour of material during electromagnetic expanding ring test, is our primary goal in this work. Five more popular constitutive models are examined, i.e., Johnson-Cook, Steinberg-Guinan, Zerilli-Armstrong, MTS, and Preston-Tonks-Wallace model. As a criterion of the selection, qualitative/quantitative agreement of the numerical results with analogous data obtained from experiment presented in the work was taken [1]. It was found that the numerical results obtained by using Steinberg-Guinan or Preston-Tonks-Wallace model gave the best agreement with experimental data.

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