Changes between Initial Version and Version 1 of Ticket #628


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Timestamp:
03/14/14 00:55:30 (10 years ago)
Author:
arango
Comment:

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  • Ticket #628

    • Property Resolution → Done
    • Property Status new → closed

  • Ticket #628 – Description

    initial v1  
    11Two new Matlab scripts were added to process sponges and nudging inverse time scales. See src:ticket:627 for detailed documentation.
    22
    3  * grid/add_sponge: % Adds enhanced viscosity and diffusion scaling variables (visc_factor and diff_factor) to an existing ROMS Grid NetCDF file.  These scales are used in an application to set sponge areas with larger horizontal mixing coefficients for the damping of high frequency noise coming from open boundary conditions or nesting.  In ROMS, these scales are used as follows:
     3 * '''grid/add_sponge.m''': Adds enhanced viscosity and diffusion scaling variables ('''visc_factor''' and '''diff_factor''') to an existing ROMS Grid NetCDF file.  These scales are used in an application to set sponge areas with larger horizontal mixing coefficients for the damping of high frequency noise coming from open boundary conditions or nesting.  In ROMS, these scales are used as follows:
    44 {{{
    55    visc2_r(i,j) = visc2_r(i,j) * visc_factor(i,j)
    … …  
    1212
    1313 '''NOTICE''' that it is more advantageous to specify these scaling factors in the ROMS Grid that coding it inside ROMS.  We can plot and adjust their values in an easy way in Matlab.
     14
     15 * '''initial/d_nudgcoef.m''': This a user modifiable script that can be used to prepare ROMS nudging inverse time scales NetCDF file.  It sets-up all the necessary parameters and variables. Users can use this as a prototype for their application.
     16
     17 Nudging to climatology can be used in ROMS for various purposes:
     18
     19  . Improve the behavior of open boundary conditions.
     20
     21  . Used in conjunction with sponges.
     22
     23  . Minimize numerical diapycnal mixing of tracers over steep bathymetry (improve T-S properties in deep water masses).  For example, we can nudge to T-S climatology is areas deeper than 1500 m.
     24
     25 The inverse nudging coefficients have units of''' 1/time'''.  The default input units in ROMS is '''1/day''' but '''1/second''' is also possible. The routine  '''get_nudgcoef.F''' will check the '''units''' attribute to compute the conversion factor for '''1/second'''. Users need to be sure the '''units''' variable attribute is consistent with the written data.
     26
     27 The variable names for the nudging coefficients is as follows:
     28 {{{
     29     M2_NudgeCoef       for 2D momentum
     30     M3_NudgeCoef       for 3D momentum
     31     temp_NudgeCoef     for potential temperature
     32     salt_NudgeCoef     for salinity
     33     ...
     34     NO3_NudgeCoef      for nitrate
     35     ...
     36     tracer_NudgeCoef   for any generic tracer
     37}}}
     38
     39 They are all defined at '''RHO'''-points. If the nudging coefficients for a specific tracer are available in the NetCDF, ROMS will read that NetCDF variable. If NOT and the generic coefficients '''tracer_NudgeCoef''' are available, ROMS will process those values instead.
     40
     41 Notice that the input switch '''LnudgeTCLM(itrc,ng)''' in ROMS input script '''ocean.in''' will control which trace to nudge in the desired grid.
     42
     43 Currently, the nudging coefficients are time invariant in ROMS.  The same scales are used for the entire simulation.