# Changeset 11531

Ignore:
Timestamp:
2019-09-11T14:35:15+02:00 (12 months ago)
Message:

update doc bdy

File:
1 edited

### Legend:

Unmodified
 r11528 Options are defined through the \nam{bdy} \nam{bdy\_dta} namelist variables. The BDY module is the core implementation of open boundary conditions for regional configurations on temperature, salinity, barotropic and baroclinic velocities, as well as ice concentration, ice and snow thicknesses. ocean temperature, salinity, barotropic-baroclinic velocities, ice-snow concentration, thicknesses, temperatures, salinity and melt ponds concentration and thickness. The BDY module was modelled on the OBC module (see \NEMO\ 3.4) and shares many features and It is possible to define more than one boundary set'' and apply different boundary conditions to each set. The number of boundary sets is defined by \np{nb\_bdy}. Each boundary set may be defined as a set of straight line segments in a namelist (\np{ln\_coords\_file}\forcode{ = .false.}) or read in from a file (\np{ln\_coords\_file}\forcode{ = .true.}). If the set is defined in a namelist, then the namelists \nam{bdy\_index} must be included separately, one for each set. If the set is defined by a file, then a \ifile{coordinates.bdy}'' file must be provided. Each boundary set can be either defined as a series of straight line segments directly in the namelist (\np{ln\_coords\_file}\forcode{ = .false.}, and a namelist block \nam{bdy\_index} must be included for each set) or read in from a file (\np{ln\_coords\_file}\forcode{ = .true.}, and a \ifile{coordinates.bdy}'' file must be provided). The coordinates.bdy file is analagous to the usual \NEMO\ \ifile{coordinates}'' file. In the example above, there are two boundary sets, the first of which is defined via a file and the second is defined in a namelist. the second is defined in the namelist. For more details of the definition of the boundary geometry see section \autoref{subsec:BDY_geometry}. For each boundary set a boundary condition has to be chosen for the barotropic solution (u2d'':sea-surface height and barotropic velocities), for the baroclinic velocities (u3d''), for the active tracers \footnote{The BDY module does not deal with passive tracers at this version} (tra''), and sea-ice (ice''). For each set of variables there is a choice of algorithm and a choice for the data, eg. for the active tracers the algorithm is set by \np{cn\_tra} and the choice of data is set by \np{nn\_tra\_dta}.\\ for the active tracers \footnote{The BDY module does not deal with passive tracers at this version} (tra''), and for sea-ice (ice''). For each set of variables one has to choose an algorithm and the boundary data (set resp. by \np{cn\_tra} and \np{cn\_tra} for tracers).\\ The choice of algorithm is currently as follows: \end{description} The main choice for the boundary data is to use initial conditions as boundary data (\np{nn\_tra\_dta}\forcode{ = 0}) or to use external data from a file (\np{nn\_tra\_dta}\forcode{ = 1}). The boundary data is either set to initial conditions (\np{nn\_tra\_dta}\forcode{ = 0}) or forced with external data from a file (\np{nn\_tra\_dta}\forcode{ = 1}). In case the 3d velocity data contain the total velocity (ie, baroclinic and barotropic velocity), the bdy code can derived baroclinic and barotropic velocities by setting \np{ln\_full\_vel}\forcode{ = .true. } For the barotropic solution there is also the option to use tidal harmonic forcing either by itself (\np{nn\_dyn2d\_dta}\forcode{ = 2}) or in addition to other external data (\np{nn\_dyn2d\_dta}\forcode{ = 3}).\\ Sea-ice salinity, temperature and age data at the boundary are constant and defined repectively by \np{rn\_ice\_sal}, \np{rn\_ice\_tem} and \np{rn\_ice\_age}. If not set to initial conditions, sea-ice salinity, temperatures and melt ponds data at the boundary can either be read in a file or defined as constant (by \np{rn\_ice\_sal}, \np{rn\_ice\_tem}, \np{rn\_ice\_apnd}, \np{rn\_ice\_hpnd}). Ice age is constant and defined by \np{rn\_ice\_age}. If external boundary data is required then the \nam{bdy\_dta} namelist must be defined. For each required variable, the filename, the frequency of the files and the frequency of the data in the files are given. Also whether or not time-interpolation is required and whether the data is climatological (time-cyclic) data.\\ Also whether or not time-interpolation is required and whether the data is climatological (time-cyclic) data. For sea-ice salinity, temperatures and melt ponds, reading the files are skipped and constant values are used if filenames are defined as {'NOT USED'}.\\ There is currently an option to vertically interpolate the open boundary data onto the native grid at run-time.