scholarly journals Considerations on Open Boundary Conditions for Regional and Coastal Ocean Models

2006 ◽  
Vol 23 (11) ◽  
pp. 1604-1613 ◽  
Author(s):  
P. Marsaleix ◽  
F. Auclair ◽  
C. Estournel
Keyword(s):  
Energy Conservation ◽  
Boundary Conditions ◽  
Radiation Condition ◽  
Coastal Ocean ◽  
Open Boundary ◽  
External Information ◽  
Advection Equation ◽  
Open Boundary Conditions ◽  
Ocean Models ◽  
Mass And Energy Conservation

Abstract This paper reviews the usual open boundary conditions (OBCs) for coastal ocean models and proposes a complete set of open boundaries based on stability criteria, on mass and energy conservation arguments, and on the ability to enforce external information. This set includes a radiation condition for barotropic variables, an equation of wave propagation for baroclinic velocities, and an advection equation for tracers. Considerations on mass and energy conservation properties suggest a suitable numerical treatment of the barotropic scheme, which is different from what is commonly used. Restoring terms, when classically added in the Sommerfeld OBCs, are not consistent with external fields. It is shown that this can be avoided if proper numerical schemes are used or if OBCs are applied on differences between the model and forcing rather than on absolute variables. Finally, this paper shows that simplistic advection-type methods for temperature and salinity should not be used in sigma coordinate models because this introduces errors in the computation of the horizontal pressure gradient.

Tools and technologies for NEMO models: the case of the Generic Interfaces developed in the framework of IMMERSE

2021 ◽  
Author(s):  
Laura Stefanizzi ◽  
Stefania Ciliberti ◽  
Mehmet Ilicak ◽  
Giovanni Coppini
Keyword(s):  
Boundary Conditions ◽  
Black Sea ◽  
Numerical Solutions ◽  
Initial Boundary ◽  
Coastal Ocean ◽  
Open Boundary ◽  
The Black Sea ◽  
Marmara Sea ◽  
Open Boundary Conditions ◽  
Model Configuration

<p>Setting new model configurations based on NEMO requires the definition of initial/boundary condition and the validation of numerical solutions. In the framework of IMMERSE H2020 project, CMCC is developing new tools and technological capacities for handling in easy and reliable way external products, such CMEMS or coastal ocean data, for research-to-operations applications. Generic Interfaces for NEMO (InterNEMO) allow for 3 main scopes: 1) to access and discover the CMEMS catalogue, including both model and observational data; 2) to manipulate accessed datasets, including coastal ocean data, to extract relevant physical information to use for setting initial/boundary conditions for a new NEMO-based configurations; 3) to prepare NEMO set of upstream files and to validate NEMO solution by using CMEMS observational datasets. InterNEMO implements also technologies to connect a NEMO user to Wekeo DIAS (https://www.wekeo.eu/) for the interoperable accessing and processing of CMEMS data. In this contribution, we present the InterNEMO architecture developed in Python via Jupyter Notebooks, to support the user/researcher to easily discover, design and configure modeling components required by the new NEMO-based configuration. InterNEMO is tested for the Black Sea hydrodynamical model configuration, developed by CMCC in the framework of the Black Sea Monitoring and Forecasting Centre (BS-MFC) for CMEMS a) to show how to access CMEMS observations through Wekeo DIAS and use them to validate numerical solutions and b) to define open boundary conditions from an unstructured grid model configuration based on Shyfem, developed for the Marmara Sea.</p>

Boundary Conditions, Data Assimilation, and Predictability in Coastal Ocean Models

2005 ◽  
Author(s):  
Roger M. Samelson ◽  
John S. Allen ◽  
Gary D. Egbert ◽  
John C. Kindle ◽  
Chris Snyder
Keyword(s):  
Data Assimilation ◽  
Boundary Conditions ◽  
Coastal Ocean ◽  
Ocean Models

scholarly journals Impurity induced scale-free localization

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Linhu Li ◽  
Ching Hua Lee ◽  
Jiangbin Gong
Keyword(s):  
Boundary Conditions ◽  
Skin Effect ◽  
Reciprocal Lattice ◽  
Periodic Boundary Conditions ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Translational Invariance ◽  
Scale Free ◽  
Special Cases ◽  
Simulation Results

AbstractNon-Hermitian systems have been shown to have a dramatic sensitivity to their boundary conditions. In particular, the non-Hermitian skin effect induces collective boundary localization upon turning off boundary coupling, a feature very distinct from that under periodic boundary conditions. Here we develop a full framework for non-Hermitian impurity physics in a non-reciprocal lattice, with periodic/open boundary conditions and even their interpolations being special cases across a whole range of boundary impurity strengths. We uncover steady states with scale-free localization along or even against the direction of non-reciprocity in various impurity strength regimes. Also present are Bloch-like states that survive albeit broken translational invariance. We further explore the co-existence of non-Hermitian skin effect and scale-free localization, where even qualitative aspects of the system’s spectrum can be extremely sensitive to impurity strength. Specific circuit setups are also proposed for experimentally detecting the scale-free accumulation, with simulation results confirming our main findings.

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