Changes between Version 15 and Version 16 of Users/Model Interfacing/AGRIF


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Timestamp:
2018-08-31T12:38:22+02:00 (2 years ago)
Author:
jchanut
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  • Users/Model Interfacing/AGRIF

    v15 v16  
    1010== Overview 
    1111 
    12 AGRIF (Adaptive Grid Refinement In Fortran) is a library that allows the seamless space and time refinement over rectangular regions in NEMO. Refinement factors can be odd or even (usually lower than 5 to maintain stability). Interaction between grid is "Two-ways" in the sense that the parent grid feeds the child grid open boundaries and the child grid provides volume averages of prognostic variables once a given number of time step is completed. 
     12AGRIF (Adaptive Grid Refinement In Fortran) is a library that allows the seamless space and time refinement over rectangular regions in NEMO. Refinement factors can be odd or even (usually lower than 5 to maintain stability). Interaction between grid is "two-ways" in the sense that the parent grid feeds the child grid open boundaries and the child grid provides volume averages of prognostic variables once a given number of time step is completed. 
    1313This pages provides guidelines how to use AGRIF in NEMO. For a more technical description of the library itself, please refer to the following page: [http://agrif.imag.fr]. 
    1414 
     
    4949== Namelist options 
    5050 
    51 Each child expects to read its own namelist so that different numerical choices can be made (these should be stored in the form 1_namelist_cfg, 2_namelist_cfg, etc... according to their rank in the grid hierarchy). Consistent time steps and number of steps with the chosen time refinement have to be provided. Specific to AGRIF is the following block: 
     51Each child grid expects to read its own namelist so that different numerical choices can be made (these should be stored in the form 1_namelist_cfg, 2_namelist_cfg, etc... according to their rank in the grid hierarchy). Consistent time steps and number of steps with the chosen time refinement have to be provided. Specific to AGRIF is the following block: 
    5252 
    5353{{{ 
     
    219219}}} 
    220220 
    221 ++ Of course, output files are now greater by 4 points in each direction. 
     221++ Output files are now greater by 4 points in each direction. 
    222222 
    223223 
    224224=== New reference configuration with AGRIF: AGRIF_DEMO  
    225225 
    226 {{{#!table class=''  style='width: 66%' 
    227226{{{#!td 
    228 {{{#!imagebox 
     227AGRIF_DEMO is based on the [wiki:Users/ReferenceConfigurations/ORCA2_LIM3_PISCES] global 2° configuration but it includes 3 online nested grids that demonstrate the overall capabilities of AGRIF in a realistic context, including nesting sea ice models.  \\ 
     228The configuration includes a 1:1 grid in the Pacific and two successively nested grids with odd and even refinement ratios over the Arctic ocean. The finest grid spanning the whole Svalbard archipelago is of particular interest to check that sea ice coupling is done properly. The 1:1 grid, used alone, is used as a benchmark to check that the solution is not corrupted by grid exchanges. \\ 
     229Note that since grids interact only at the baroclinic time level, numerically exact results can not be achieved in the 1:1 case. One has to switch to a fully explicit in place of a split explicit free surface scheme in order to retrieve perfect reproducibility. 
     230}}} 
     231{{{#!td style="border: none;" 
    229232[[Image(wiki:Users/ModelInterfacing/AGRIF:AGRIF_DEMO.jpg,width=600)]] 
    230 }}} 
    231 }}} 
    232 {{{#!td  style='width: 3%' 
    233 }}} 
    234 {{{#!td 
    235 AGRIF_DEMO is based on the [wiki:Users/ReferenceConfigurations/ORCA2_LIM3_PISCES] global 2° configuration but it includes 3 online nested grids that demonstrate the overall capabilities of AGRIF in a realistic context, including nesting sea ice models. 
    236  
    237 The configuration includes a 1:1 grid in the Pacific and two successively nested grids with odd and even refinement ratios over the Arctic ocean. The finest grid spanning the whole Svalbard archipelago is of particular interest to check that sea ice coupling is done properly. The 1:1 grid, used alone, is used as a benchmark to check that the solution is not corrupted by grid exchanges. 
    238  
    239 Note that since grids interact only at the baroclinic time level, numerically exact results can not be achieved in the 1:1 case. One has to switch to a fully explicit in place of a split explicit free surface scheme in order to retrieve perfect reproducibility. 
    240 }}} 
    241233}}} 
    242234 
     
    264256 * tests/VORTEX: 
    265257 
    266 This test case illustrates the propagation of an anticyclonic eddy over a Beta plan and a flat bottom. It is implemented here with an online refined subdomain (1:3) out of which the vortex propagates. It serves as a benchmark for quantitative estimates of nesting errors as in Debreu et al. (2012), Penven et al. (2006) or Spall and Holland (1991). The animation below (sea level anomaly in meters) illustrates with two 1:2 successfully nested grids how the vortex smoothly propagates out of the refined grids.  
     258This test case illustrates the propagation of an anticyclonic eddy over a Beta plan and a flat bottom. It is implemented here with an online refined subdomain (1:3) out of which the vortex propagates. It serves as a benchmark for quantitative estimates of nesting errors as in Debreu et al. (2012), Penven et al. (2006) or Spall and Holland (1991). The animation below (sea level anomaly in meters) illustrates with two 1:2 successively nested grids how the vortex smoothly propagates out of the refined grids.  
    267259  
    268260   {{{#!td style="border: none;" 
    269261   [[Image(wiki:Users/ModelInterfacing/AGRIF:VORTEX_anim.gif,width=600)]] 
    270262   }}} 
     263 
     264 
     265== References 
     266Debreu, L., P. Marchesiello, P. Penven and G. Cambon, 2012: Two-way nesting in split-explicit ocean models: Algorithms, implementation and validation. Ocean Modelling, 49-50, 1-21. [https://doi.org/10.1016/j.ocemod.2012.03.003] 
     267 
     268Penven, P., L. Debreu, P. Marchesiello and J. C. McWilliams, 2006: Evaluation and application of the ROMS 1-way embedding procedure to the central california upwelling system. Ocean Modelling, 12, 157-187. [https://doi.org/10.1016/j.ocemod.2005.05.002] 
     269 
     270Spall, M. A. and W. R. Holland, 1991: A Nested Primitive Equation Model for Oceanic Applications. J. Phys. Ocean., 21, 205-220. [https://doi.org/10.1175/1520-0485(1991)021<0205:ANPEMF>2.0.CO;2]    
     271Spall and Holland (1991)