scholarly journals Improve Ocean Modelling Software NEMO 4.0 benchmarking and communication efficiency

2021 ◽  
Author(s):  
Gaston Irrmann ◽  
Sébastien Masson ◽  
Éric Maisonnave ◽  
David Guibert ◽  
Erwan Raffin
Keyword(s):  
Free Surface ◽  
Surface Pressure ◽  
Distributed Memory ◽  
Semiconductor Industry ◽  
Ocean Model ◽  
Ocean Modelling ◽  
Parallel Decomposition ◽  
Communication Efficiency ◽  
Recent Trends ◽  
Computing Performance

Abstract. Communications in distributed memory supercomputers are still limiting scalability of geophysical models. Consid-ering the recent trends of the semiconductor industry, we think this problem is here to stay. We present the optimisations thathave been implemented in the actual 4.0 reference version of the ocean model NEMO 4.0 to improve its scalability. Thanksto the collaboration of oceanographers and HPC experts, we identified and removed the unnecessary communications in twobottleneck routines, the computation of free surface pressure gradient and the forcing in the straights or unstructured open5boundaries. Since a wrong parallel decomposition choice could undermine computing performance, we impose its automaticdefinition in all cases, including when subdomains containing land points only are excluded from the decomposition. For asmaller audience of developers and vendors, we propose a new benchmark configuration, easy to use while offering the fullcomplexity of operational versions.

scholarly journals WAVETRISK-2.1: an adaptive dynamical core for ocean modelling

2021 ◽  
Author(s):  
Nicholas Keville-Reynolds Kevlahan ◽  
Florian Lemarié
Keyword(s):  
Free Surface ◽  
Shallow Water ◽  
Time Integration ◽  
Ocean Model ◽  
Mesh Adaptivity ◽  
Time Step ◽  
Vertical Coordinate ◽  
Slip Boundary ◽  
Modelling Framework ◽  
Atmosphere Model

Abstract. This paper introduces WAVETRISK-2.1 (i.e. WAVETRISK-OCEAN), an incompressible version of the atmosphere model wavetrisk-1.x with free-surface. This new model is built on the same wavelet-based dynamically adaptive core as wavetrisk, which itself uses DYNANICO's mimetic vector-invariant multilayer rotating shallow water formulation. Both codes use a Lagrangian vertical coordinate with conservative remapping. The ocean variant solves the incompressible multilayer shallow water equations with inhomogeneous density layers. Time integration uses barotropic--baroclinic mode splitting via an semi-implicit free surface formulation, which is about 34–44 times faster than an unsplit explicit time-stepping. The barotropic and baroclinic estimates of the free surface are reconciled at each time step using layer dilation. No slip boundary conditions at coastlines are approximated using volume penalization. The vertical eddy viscosity and diffusivity coefficients are computed from a closure model based on turbulent kinetic energy (TKE). Results are presented for a standard set of ocean model test cases adapted to the sphere (seamount, upwelling and baroclinic turbulence). An innovative feature of wavetrisk-ocean is that it could be coupled easily to the wavetrisk atmosphere model, thus providing a first building block toward an integrated Earth-system model using a consistent modelling framework with dynamic mesh adaptivity and mimetic properties.

Practical Evaluation of Steady Flow Resulting from a Free-Surface Pressure Patch

2009 ◽  
Vol 53 (03) ◽  
pp. 137-150
Author(s):  
Francis Noblesse ◽  
Gérard Delhommeau ◽  
Chi Yang
Keyword(s):  
Free Surface ◽  
Surface Pressure ◽  
High Speed ◽  
Surface Effect ◽  
Practical Method ◽  
Analytical Approximation ◽  
Surface Boundary ◽  
Steady Flows ◽  
Local Flow ◽  
The Green Function

The linearized potential flow resulting from a distribution of pressure that advances at constant speed along a straight path at the free surface of calm water, of effectively infinite depth and lateral extent, is considered. A practical method for evaluating the free-surface elevation caused by the moving free-surface pressure patch—which can be used to model steady flows of air-cushion vehicles, high-speed planing boats, surface-effect ships, and some types of hybrid ships—is given. The key ingredient of this method is a highly simplified analytical approximation to the local-flow component in the expression for the Green function associated with the classic Michell-Kelvin linearized free-surface boundary condition.

scholarly journals Implementation of a time-dependent bathymetry in a free-surface ocean model: Application to internal wave generation

2014 ◽  
Vol 80 ◽  
pp. 1-9 ◽  
Author(s):  
F. Auclair ◽  
L. Bordois ◽  
Y. Dossmann ◽  
T. Duhaut ◽  
C. Estournel ◽  
...  
Keyword(s):  
Free Surface ◽  
Internal Wave ◽  
Wave Generation ◽  
Ocean Model ◽  
Time Dependent ◽  
Model Application ◽  
Surface Ocean ◽  
Internal Wave Generation

scholarly journals Simulation of free surface flows in a distributed memory environment

1999 ◽  
Vol 103 (1) ◽  
pp. 77-92
Author(s):  
JoséA. Cuminato ◽  
Antonio Castelo Filho ◽  
Maurilio Boaventura ◽  
Murilo F. Tomé
Keyword(s):  
Free Surface ◽  
Distributed Memory ◽  
Free Surface Flows ◽  
Surface Flows

scholarly journals Linearized planing-surface theory with surface tension. Part I: Smooth detachment

1982 ◽  
Vol 23 (3) ◽  
pp. 241-258 ◽  
Author(s):  
E. O. Tuck
Keyword(s):  
Surface Tension ◽  
Integral Equation ◽  
Free Surface ◽  
Surface Pressure ◽  
Leading Edge ◽  
Surface Slope ◽  
Surface Theory ◽  
Surface Pressure Distribution ◽  
Jump Discontinuities ◽  
Impulsive Pressure

AbstractIn the absence of surface tension, the problem of determining a travelling surface pressure distribution that displaces a portion of the free surface in a prescribed manner has been solved by several authors, and this “planing-surface” problem is reasonably well understood. The effect of inclusion of surface tension is to change, in a dramatic way, the singularity in the integral equation that describes the problem. It is now necessary in general to allow for isolated impulsive pressure, as well as a smooth distribution over the wetted length. Such pressure points generate jump discontinuities in free-surface slope. Numerical results are obtained here for a class of problems in which there is a single impulse located at the leading edge of the planing surface and detachment with continuous slope at the trailing edge. These results do not appear to approach the classical results in the limit as the surface tension approaches zero, a paradox that is resolved in Part II, which follows.

scholarly journals GO5.0: the joint NERC–Met Office NEMO global ocean model for use in coupled and forced applications

2014 ◽  
Vol 7 (3) ◽  
pp. 1069-1092 ◽  
Author(s):  
A. Megann ◽  
D. Storkey ◽  
Y. Aksenov ◽  
S. Alderson ◽  
D. Calvert ◽  
...  
Keyword(s):  
Land Surface ◽  
Short Range ◽  
Mixed Layer Depth ◽  
Research Programme ◽  
Ocean Model ◽  
Seasonal Forecasting ◽  
Global Ocean ◽  
Ocean Modelling ◽  
Standard Configuration ◽  
Ocean Forecasting

Abstract. We describe a new Global Ocean standard configuration (GO5.0) at eddy-permitting resolution, developed jointly between the National Oceanography Centre and the Met Office as part of the Joint Ocean Modelling Programme (JOMP), a working group of the UK's National Centre for Ocean Forecasting (NCOF) and part of the Joint Weather and Climate Research Programme (JWCRP). The configuration has been developed with the seamless approach to modelling in mind for ocean modelling across timescales and for a range of applications, from short-range ocean forecasting through seasonal forecasting to climate predictions as well as research use. The configuration has been coupled with sea ice (GSI5.0), atmosphere (GA5.0), and land-surface (GL5.0) configurations to form a standard coupled global model (GC1). The GO5.0 model will become the basis for the ocean model component of the Forecasting Ocean Assimilation Model, which provides forced short-range forecasting services. The GC1 or future releases of it will be used in coupled short-range ocean forecasting, seasonal forecasting, decadal prediction and for climate prediction as part of the UK Earth System Model. A 30-year integration of GO5.0, run with CORE2 (Common Ocean-ice Reference Experiments) surface forcing from 1976 to 2005, is described, and the performance of the model in the final 10 years of the integration is evaluated against observations and against a comparable integration of an existing standard configuration, GO1. An additional set of 10-year sensitivity studies, carried out to attribute changes in the model performance to individual changes in the model physics, is also analysed. GO5.0 is found to have substantially reduced subsurface drift above the depth of the thermocline relative to GO1, and also shows a significant improvement in the representation of the annual cycle of surface temperature and mixed layer depth.

Waveless Free-Surface Pressure Distributions

1985 ◽  
Vol 29 (03) ◽  
pp. 151-158
Author(s):  
J.-M. Vanden Broeck ◽  
E. O. Tuck
Keyword(s):  
Free Surface ◽  
Surface Pressure ◽  
Free Surface Flows ◽  
Two Dimensional ◽  
Surface Flows ◽  
Pressure Distributions ◽  
Potential Applications ◽  
Linear And Nonlinear ◽  
Uniform Stream

Linear and nonlinear studies are made of two-dimensional free-surface flows under gravity, in which a disturbance is caused to an otherwise uniform stream by a distribution of pressure over the free surface. In general, such a disturbance creates a system of trailing waves. There are special disturbances that do not, however, and some categories of such disturbances are discussed here. This work has potential applications to design of splashless ship bows.

WAVETRISK-OCEAN: an adaptive dynamical core for ocean modelling

2021 ◽  
Author(s):  
Kevlahan Nicholas
Keyword(s):  
Free Surface ◽  
Shallow Water ◽  
Time Integration ◽  
Ocean Model ◽  
Time Step ◽  
Vertical Coordinate ◽  
Modelling Framework ◽  
Standard Set ◽  
Atmosphere Model ◽  
Multilayer Shallow Water Equations

<p>This talk introduces WAVETRISK-OCEAN, an incompressible version of the atmosphere model WAVETRISK.  This new model is built on the same wavelet-based dynamically adaptive core as WAVETRISK, which itself uses DYNAMICO's mimetic vector-invariant multilayer shallow water formulation. Both codes use a Lagrangian vertical coordinate with conservative remapping.  The ocean variant solves the incompressible multilayer shallow water equations with a Ripa type thermodynamic treatment of horizontal density gradients.  Time integration uses barotropic-baroclinic mode splitting via an implicit free surface formulation, which is about 15 times faster than explicit time stepping.  The barotropic and baroclinic estimates of the free surface are reconciled at each time step using layer dilation. No slip boundary conditions at coastlines are approximated using volume penalization.  Results are presented for a standard set of ocean model test cases adapted to the sphere (seamount,  upwelling and baroclinic jet) as well as  turbulent wind-driven gyre flow in simplified geometries.  An innovative feature of WAVETRISK-OCEAN is that it could be coupled easily to the WAVETRISK atmosphere model, providing a simple integrated Earth system model using a consistent modelling framework.</p>

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