# Changeset 11534

Ignore:
Timestamp:
2019-09-11T15:38:28+02:00 (13 months ago)
Message:

small debug on doc

File:
1 edited

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 r11531 \begin{description} \item[free-slip boundary condition (\np{rn\_shlat}\forcode{ = 0}):] the tangential velocity at \item[free-slip boundary condition (\np{rn\_shlat}\forcode{=0}):] the tangential velocity at the coastline is equal to the offshore velocity, \ie\ the normal derivative of the tangential velocity is zero at the coast, (\autoref{fig:LBC_shlat}-a). \item[no-slip boundary condition (\np{rn\_shlat}\forcode{ = 2}):] the tangential velocity vanishes at the coastline. \item[no-slip boundary condition (\np{rn\_shlat}\forcode{=2}):] the tangential velocity vanishes at the coastline. Assuming that the tangential velocity decreases linearly from the closest ocean velocity grid point to the coastline, %----------------------------------------------------------------------------------------------- Options are defined through the \nam{bdy} \nam{bdy\_dta} namelist variables. Options are defined through the \nam{bdy} and \nam{bdy\_dta} namelist variables. The BDY module is the core implementation of open boundary conditions for regional configurations on ocean temperature, salinity, barotropic-baroclinic velocities, ice-snow concentration, thicknesses, temperatures, salinity and melt ponds concentration and thickness. \label{subsec:BDY_namelist} The BDY module is activated by setting \np{ln\_bdy}\forcode{ = .true.} . The BDY module is activated by setting \np{ln\_bdy}\forcode{=.true.} . 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 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). (\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 (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 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).\\ For each set of variables one has to choose an algorithm and the boundary data (set resp. by \np{cn\_tra} and \np{nn\_tra\_dta} for tracers).\\ The choice of algorithm is currently as follows: 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}). (\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. } 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}).\\ itself (\np{nn\_dyn2d\_dta}\forcode{=2}) or in addition to other external data (\np{nn\_dyn2d\_dta}\forcode{=3}).\\ 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}. There is currently an option to vertically interpolate the open boundary data onto the native grid at run-time. If \np{nn\_bdy\_jpk} $< -1$, it is assumed that the lateral boundary data are already on the native grid. If \np{nn\_bdy\_jpk}$<-1$, it is assumed that the lateral boundary data are already on the native grid. However, if \np{nn\_bdy\_jpk} is set to the number of vertical levels present in the boundary data, a bilinear interpolation onto the native grid will be triggered at runtime. \jp{jpinft} give the start and end $i$ indices for each segment with similar for the other boundaries. These segments define a list of $T$ grid points along the outermost row of the boundary ($nbr\,=\, 1$). The code deduces the $U$ and $V$ points and also the points for $nbr\,>\, 1$ if \np{nn\_rimwidth}\forcode{ > 1}. The code deduces the $U$ and $V$ points and also the points for $nbr\,>\, 1$ if \np{nn\_rimwidth}\forcode{>1}. The boundary geometry may also be defined from a \ifile{coordinates.bdy}'' file. There is an option to force the total volume in the regional model to be constant. This is controlled  by the \np{ln\_vol} parameter in the namelist. A value of \np{ln\_vol}\forcode{ = .false.} indicates that this option is not used. A value of \np{ln\_vol}\forcode{=.false.} indicates that this option is not used. Two options to control the volume are available (\np{nn\_volctl}). If \np{nn\_volctl}\forcode{ = 0} then a correction is applied to the normal barotropic velocities around the boundary at If \np{nn\_volctl}\forcode{=0} then a correction is applied to the normal barotropic velocities around the boundary at each timestep to ensure that the integrated volume flow through the boundary is zero. If \np{nn\_volctl}\forcode{ = 1} then the calculation of the volume change on If \np{nn\_volctl}\forcode{=1} then the calculation of the volume change on the timestep includes the change due to the freshwater flux across the surface and the correction velocity corrects for this as well.