Personal tools


From MohidWiki

Jump to: navigation, search

The AssimilationZones is an application used for generating assimilation decay coefficients (also called relaxation times) files, usable in MOHID Water to perform relaxation of hydrodynamic and water properties fields to a reference field (e.g. a father model domain solution, a climatological field).

Running options for this application are specified by the user in a input file named AssimilationZones.dat.


Typical use:

3D decay coefficients files are desirable to perform temperature assimilation on MOHID Water at the surface layer based on climatology fields, emulating the consideration of heat fluxes in the water-air interface which are in equilibrium relatively to the climatological fields.

This application can be used for less orthodox ends such as in the design of viscosity sponges files to attenuate the gradient of velocity (aim is to reduce the reflection of perturbations to the inner domain due to boundary).

Data input requirements:


Input file (AssimilationZones.dat)

IN_BATIM                 : ... (path/name of grid data bathymetry file of domain to which
                                decay coefficients are to be referred)
OUT_FILE                 : ... (path/name of coefficients/grid data files to be created)

SURROUND                 : 0/1 (1(default)=define assimilation zone in grid outer limits)
(if SURROUND : 1:) 
NUMBER_CELLS             : ... (integer number of assimilation cells in XX direction)
ASSIMILATION_COEFS       : ... (decay coefficients (outside-inside) in seconds, one per column)

SURFACE_FORCING          : 0/1 (1=assimilate values in the surface layer; 0 = default)
SURFACE_COEF             : ... (decay coefficient (seconds) for the surface layer)
LAYERS_NUMBER            : ... (number of layers for 3D decay coefficients)

TYPE_Z                   : 0/1 (1(default)=output refers to cells center)
TYPE_U                   : 0/1 (1=output refers to cells faces in XX direction; 0 = default)
TYPE_V                   : 0/1 (1=output refers to cells faces in YY direction; 0 = default)

WEST                     : 0/1 (1(default)=decay values in the west boundary)
EAST                     : 0/1 (1(default)=decay values in the east boundary)
SOUTH                    : 0/1 (1(default)=decay values in the south boundary)
NORTH                    : 0/1 (1(default)=decay values in the north boundary)

DEFAULTVALUE             : ... (default value in seconds assumed for decay coefficients; 
                                1e32 s. = default)

MINIMUM_DOMINATES        : 0/1 (1(default)=lower decay coefficients dominate over the higher

NO_ASSIMILATION_ZONE     : 0/1 (1=use a polygon file to define where assimilation is not to be
NO_ASSIMILATION_FILE     : ... (path/name to polygon file defining no assimilation zone)

WRITE_AS_GRID_DATA       : 0/1 (1(default)=write grid data regular format; only if TYPE_Z : 1;
                                this grid data file can be viewed in MOHID GIS to check
                                coefficient values)
WRITE_IN_INDICES_FORMAT  : 0/1 (1(default)=write as [i],[j],[value] format)

- for any coefficients files to be generated either SURROUND : 1 or SURFACE_FORCING : 1
  options must be chosen;

- in case of SURROUND : 1 option the keywords NUMBER_CELLS and ASSIMILATION_COEFS must be

- if SURFACE_FORCING : 1 then 3D decay coefficients files are produced with the number of
  vertical layers specified in LAYERS_NUMBER; in practice all layers have the same values for
  decay coefficients except for the surface layer which takes into account the info provided

- for 3D decay coefficients files to be produced should always be specified SURFACE_FORCING :
  1; if no special coefficients are intended for the surface layer then convenient
  instructions must be provided through SURFACE_COEF and MINIMUM_DOMINATES keywords (see    
  previous remark);

- the value specified in DEFAULTVALUE is used for decay coefficients in cells not specified 
  by the SURROUND or SURFACE_FORCING keywords.


IN_BATIM                 : Outfall.dat
OUT_FILE                 : OutfallCoefs.dat

SURROUND                 : 1
NUMBER_CELLS             : 11
ASSIMILATION_COEFS       : 3e4 3e4 1e5 3e5 1e6 3e6 1e7 3e7 1e8 3e8 1e9

TYPE_Z                   : 1
TYPE_U                   : 0
TYPE_V                   : 0



DEFAULTVALUE             : 1e9

SURFACE_FORCING          : 1
SURFACE_COEF             : 1e6

LAYERS_NUMBER            : 38