Changes between Initial Version and Version 1 of Ticket #627


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Timestamp:
03/13/14 17:31:32 (10 years ago)
Author:
arango
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  • Ticket #627 – Description

    initial v1  
    4242 Again, users may use new Matlab script '''add_sponge.m''' to append the sponge variables to their application '''GRID''' NetCDF file.  Notice that you can easily plot their values to verify the desired distribution. The values of '''diff_factor''' must be positive and defined at '''RHO'''-points.  Usually their values are linearly tapered from '''one''' or '''zero''' at the inner sponge edge (interior points) to the desired maximum factor (>1) at the outer sponge edge (like domain perimeter). If a factor of '''zero''' is set over the interior points, the viscosity will be turned '''OFF''' over such points. Contrarily if a factor of '''one''' is set over the interior points, the diffusivity will be that set in '''ocean.in''' and passive models (biology, sediment) input scripts ('''tnu2'''/'''tnu4''') and post-processed in '''ini_hmixcoef.F''' (if scaled by grid size with '''DIFF_GRID''').
    4343
     44 '''WARNING''': The routine '''ini_hmixcoef.F''' was modified. It initializes the viscosity and diffusion arrays with the constant (uniform) values specified in standard input file(s). Then if '''VISC_GRID''' and/or '''DIFF_GRID''' are activated, it scales the horizontal mixing values according to the maximum grid size; the value read from standard input is assigned to cell with the larger area. Finally, if '''!LuvSponge(ng)''' and/or '''!LtracerSponge(itrc,ng)''' are turned '''ON''' and '''ANA_SPONGE''' is not defined, it multiples the horizontal mixing arrays with the sponge factors '''visc_factor''' and '''diff_factor''' described above. Check routine for more details.
     45
     46 Consequently, the header file '''ana_hmixcoef.h''' is deprecated and replaced with '''ana_sponge.h'''.  So if you were used this capability before in older ROMS versions, you need to code your sponge areas in the new header file '''ana_sponge.h'''.  This is a much simpler file.  Notice that the routine '''ini_hmixcoef''' is called before than '''ana_sponge''' is called.  Therefore, users have two options: ('''1''') completely overwrite the horizontal mixing coefficient assigned earlier in '''ini_hmixcoef''', or ('''2''') only increase horizontal mixing in the sponge areas. The sponge areas in '''ana_sponge''' can be coded as a non-dimensional factor as it is done in '''ini_hmixcoef''' with '''visc_factor''' and '''diff_factor'''. Or a complete overwrite, which is not recommended if either '''VISC_GRID''' and '''DIFF_GRID''' are activated.
     47
     48 Again, it is much easier to add the sponge scales '''visc_factor''' and '''diff_factor''' to the application GRID NetCDF file. '''Please follow this advice.
     49'''
     50
    4451----
    4552
    … …  
    5764 The switches for the biological and sediment tracers are specified in their respective input scripts. These climatology processing switches are either used to read climatology from a NetCDF file or to set their values with analytical functions. The climatology fields can be used for open boundary conditions, nudging in sponge areas, nudging relaxation terms, and horizontal mixing (tracers only).
    5865
    59  The sea-surface height (SSH) climatology. '''CLIMA(ng)%ssh''', is not used but it is kept for future use. The nudging of SSH on the free-surface governing equation (vertically integrated continuity equation) is '''not''' allowed because it violates mass/volume conservation. Recall that the time rate of change of free-surface is computed from the divergence of '''ubar''' and '''vbar'''.  If such nudging term is required, it needs to be specified on the momentum equations for ('''u''','''v''') and/or ('''ubar''','''vbar'''). If done on ('''u''','''v''') only, its effects enter the 2D momentum equations via the residual vertically integrated forcing term.
     66 The sea-surface height (SSH) climatology. '''CLIMA(ng)%ssh''', is not used but it is kept for future use. The nudging of SSH on the free-surface governing equation (vertically integrated continuity equation) is '''not''' allowed because it violates mass/volume conservation. Recall that the time rate of change of free-surface is computed from the divergence of '''ubar''' and '''vbar'''.  If such nudging term is required, it needs to be specified on the momentum equations for ('''u''','''v''') and/or ('''ubar''','''vbar'''). If done on ('''u''','''v''') only, its effects enter the 2D momentum equations via the residual vertically integrated forcing terms ('''rufrc''', '''rvfrc''').
    6067
    61  The '''LtracerCLM''' switches determine which trace to process and the size of the fourth dimension of '''CLIMA(ng)%tclm'''.  It is only dimensioned to the number of tracers to process, '''NTCLM(ng)''', in order to reduce memory usage. An internal counter, '''ic''', is used in the code to use the correct tracer:
     68 The '''LtracerCLM''' switches determine which tracer to process and the size of the fourth dimension of '''CLIMA(ng)%tclm'''.  It is only dimensioned to the number of tracers to process, '''NTCLM(ng)''', in order to reduce memory usage. An internal counter, '''ic''', is used in the code to use the correct tracer. For example, in '''step3d_t''' we have:
    6269 {{{
    6370     ic=0
    … …  
    94101  LnudgeTCLM == F F                        ! temperature, salinity, inert
    95102}}}
     103 The switches for biological and sediment tracer are specified in their respective input scripts.  Users also need activate the respective switches to process the climatology fields to nudge: '''Lm2CLM''', '''Lm3CLM''', and '''LtracerCLM''', respectively.
     104
     105 '''Nudging Inverse Time Scales''': The inverse nudging scales (1/time) can be read from new NetCDF file '''NUDNAME''' in '''ocean.in''':
     106 {{{
     107 ! Input climatology nudging coefficients file name.
     108
     109     NUDNAME == ocean_nud.nc
     110}}}
     111 or set with analytical functions used '''new''' CPP option '''ANA_NUDGCOEF'''.  The inverse nudging scales are stored in ROMS in the following variables:
     112 {{{
     113      CLIMA(ng) % M2nudgcof(i,j)           2D momentum
     114      CLIMA(ng) % M3nudgcof(i,j,k)         3D momentum
     115      CLIMA(ng) %  Tnudgcof(i,j,k,itrc)    Tracers
     116}}}
     117 Notice that now the nudging scales for 3D momentum and tracers has a depth dependency. This will be handy, for example, when relaxing temperature and salinity to climatology below an specific depth (say, z=-2000m).
     118
     119 In order to allow complex nudging distributions, I '''highly recommend''' users to set the nudging inverse time scales outside of ROMS and write into the '''NUDNAME''' NetCDF file.  The metadata for the NetCDF variables is as follows:
     120 {{{
     121        double M2_NudgeCoef(eta_rho, xi_rho) ;
     122                M2_NudgeCoef:long_name = "2D momentum inverse nudging coefficients" ;
     123                M2_NudgeCoef:units = "day-1" ;
     124                M2_NudgeCoef:coordinates = "xi_rho eta_rho " ;
     125
     126        double M3_NudgeCoef(s_rho, eta_rho, xi_rho) ;
     127                M3_NudgeCoef:long_name = "3D momentum inverse nudging coefficients" ;
     128                M3_NudgeCoef:units = "day-1" ;
     129                M3_NudgeCoef:coordinates = "xi_rho eta_rho s_rho " ;
     130
     131        double tracer_NudgeCoef(s_rho, eta_rho, xi_rho) ;
     132                tracer_NudgeCoef:long_name = "generic tracer inverse nudging coefficients" ;
     133                tracer_NudgeCoef:units = "day-1" ;
     134                tracer_NudgeCoef:coordinates = "xi_rho eta_rho s_rho " ;
     135
     136        double temp_NudgeCoef(s_rho, eta_rho, xi_rho) ;
     137                temp_NudgeCoef:long_name = "temp inverse nudging coefficients" ;
     138                temp_NudgeCoef:units = "day-1" ;
     139                temp_NudgeCoef:coordinates = "xi_rho eta_rho s_rho " ;
     140
     141        double salt_NudgeCoef(s_rho, eta_rho, xi_rho) ;
     142                salt_NudgeCoef:long_name = "salt inverse nudging coefficients" ;
     143                salt_NudgeCoef:units = "day-1" ;
     144                salt_NudgeCoef:coordinates = "xi_rho eta_rho s_rho " ;
     145}}}
     146 A new routine get_nudgcoef.F is added to read these nudging inverse time scales. This routine will check the '''units''' attribute to convert the scales to 1/second.  If the nudging scales for a specific tracer are available (say '''salt_NudgCoef''') it will read that NetCDF variable. If '''not and''' the generic scales are available ('''tracer_NudgeCoef'''), it will process those values instead.  This strategy will give a lot of flexibility when setting nudging for a particular application.  The generic '''tracer_NudgeCoef''' variable is useful when nudging passive (biology and sediment) tracers.