ROMS/TOMS: 
Regional Ocean Modeling System 
The Regional Ocean Model System (http://www.myroms.org/)
is a freesurface, hydrostatic, primitive equation ocean model
that uses stretched, terrainfollowing coordinates in the vertical
and orthogonal curvilinear coordinates in the horizontal.
Initially, it was based on the Scoordinate Rutgers University Model (SCRUM)
described by Song and Haidvogel (1994). ROMS was completely rewritten to improve
both its numerics and efficiency in single and multithreaded computer architectures.
It also was expanded to include a variety of new features including:
 highorder advection schemes;
 accurate pressure gradient algorithms;
 several subgridscale parameterizations;
 atmospheric, oceanic, and benthic boundary layers;
 biological modules;
 radiation boundary conditions;
 and data assimilation.
Test case: Model implementation for the
Hamriyah Free Economic Zone, UAE, Reverse Osmosis desalination plant, inner harbor outfall scenario
Model Grid
The model uses Cartesian grid with horizontal resolution of 10 m.
Domain size: 400x400 grid points with 7 vertical levels.
Sigma (terrainfollowing) levels are uniformly distributed.
Topography is extracted from prepared bathymetry file for HFZ domain.
Land/sea masking for rho, u, v and psi grids are calculated accordingly.
Grid parameters: pm, pn, x_rho, y_rho, x_psi, y_psi, x_u, y_u, x_v, y_v
are extracted from analytical grid calculated by the model using ANA_GRID option.
Coriolis factor is set to constant f=0.0001 s1
Model options
for setup with open boundary conditions,
analytical tides, analytical salinity input and mm5 surface forcing:
ANA_BSFLUX  Analytical kinematic bottom salinity flux. 
ANA_BTFLUX  Analytical kinematic bottom temperature flux. 
ANA_FSOBC  Analytical freesurface boundary conditions. 
ANA_INITIAL  Analytical initial conditions. 
ANA_M2OBC  Analytical 2D momentum boundary conditions. 
ANA_PSOURCE  Analytical point sources and sinks. 
ANA_TOBC  Analytical tracers boundary conditions. 
ASSUMED_SHAPE  Using assumedshape arrays. 
AVERAGES  Writing out timeaveraged fields 
AVERAGES_AKS  Writing out timeaveraged vertical Sdiffusion. 
AVERAGES_AKT  Writing out timeaveraged vertical Tdiffusion. 
BULK_FLUXES  Surface bulk fluxes parametererization. 
DJ_GRADPS  Parabolic Splines density Jacobian (Shchepetkin, 2002). 
DOUBLE_PRECISION  Double precision arithmetic. 
EASTERN_WALL  Wall boundary at Eastern edge. 
EMINUSP  Compute Salt Flux using EP. 
LMD_BKPP  KPP bottom boundary layer mixing. 
LMD_CONVEC  LMD convective mixing due to shear instability. 
LMD_MIXING  Large/McWilliams/Doney interior mixing. 
LMD_NONLOCAL  LMD convective nonlocal transport. 
LMD_RIMIX  LMD diffusivity due to shear instability. 
LMD_SKPP  KPP surface boundary layer mixing. 
LONGWAVE_OUT  Compute outgoing longwave radiation internally. 
MASKING  Land/Sea masking. 
MIX_GEO_TS  Mixing of tracers along geopotential surfaces. 
NONLINEAR  Nonlinear Model. 
NONLIN_EOS  Nonlinear Equation of State for seawater. 
NORTH_FSCHAPMAN  Northern edge, freesurface, Chapman condition. 
NORTH_M2FLATHER  Northern edge, 2D momentum, Flather condition. 
NORTH_M3RADIATION  Northern edge, 3D momentum, radiation condition. 
NORTH_TRADIATION  Northern edge, tracers, radiation condition. 
_OPENMP  OpenMP parallel sharedmemory directives. 
POWER_LAW  Powerlaw shape timeaveraging barotropic filter. 
PROFILE  Time profiling activated . 
!RST_SINGLE  Double precision fields in restart NetCDF file. 
SALINITY  Using salinity. 
SOLVE3D  Solving 3D Primitive Equations. 
SOUTH_FSCHAPMAN  Southern edge, freesurface, Chapman condition. 
SOUTH_M2FLATHER  Southern edge, 2D momentum, Flather condition. 
SOUTH_M3RADIATION  Southern edge, 3D momentum, radiation condition. 
SOUTH_TRADIATION  Southern edge, tracers, radiation condition. 
SPLINES  Conservative parabolic spline reconstruction. 
STATIONS  Writing out station data. 
TS_A4HADVECTION  Fourthorder Akima horizontal advection of tracers. 
TS_A4VADVECTION  Fourthorder Akima vertical advection of tracers. 
TS_DIF2  Harmonic mixing of tracers. 
TS_PSOURCE  Tracers point sources and sinks. 
UV_ADV  Advection of momentum. 
UV_COR  Coriolis term. 
UV_U3HADVECTION  Thirdorder upstream horizontal advection of 3D momentum. 
UV_C4VADVECTION  Fourthorder centered vertical advection of momentum. 
UV_QDRAG  Quadratic bottom stress. 
UV_PSOURCE  Mass point sources and sinks. 
VAR_RHO_2D  Variable density barotropic mode. 
WEST_FSCHAPMAN  Western edge, freesurface, Chapman condition. 
WEST_M2FLATHER  Western edge, 2D momentum, Flather condition. 
WEST_M3RADIATION  Western edge, 3D momentum, radiation condition. 
WEST_TRADIATION  Western edge, tracers, radiation condition. 
WET_DRY  Wetting and drying activated. 
Initial conditions
Initial temperature and salinity are set to background values.
Background temperature T0 = 25°C.
Background salinity S0 = 40 psu.
Initial velocities and sea surface height are set to zero.
Lateral boundary conditions
In scenario with open boundary conditions, South, North and West boundary have prescribed radiation condition for tracers and 3D momentum, Chapman condition for sea surface height and Flather conditions for 2D momentum.
Tides are prescribed on the northern boundary with analytical function:
ssh = A * sin( 2 * pi * time / (12 * 3600) ),
where A= 0.05m (0.9 m for scenario "HFZ tides MM5").
No velocities are prescribed on the lateral boundaries, while tracer values are set to background values.
In scenario with closed boundary conditions, walls are defined for all lateral boundaries (zero velocities, no radiation).
Surface boundary conditions
In scenarios with MM5 surface forcing, realtime MM5 forecast output is used to force the model. MM5 timeseries at ROMS HFZ longitude/latitude are extracted for 24 hours, output every 60 minutes.
(Note: maximal resolution of MM5 output is 3 km, while ROMS HFZ domain extent is 4km).
Following variables are extracted from MM5 and interpolated on ROMS HFZ grid:
 PSTARTCRS, PTORP, PP  pressure
 T2  temperature at 2 m
 Q2  humidity at 2 m
 U10  uwind at 10 m
 V10  vwind at 10m
 SWDOWN  shortwave downward radiation
 LWDOWN  longwave downward radiation
 RAIN_CON, RAIN_NON  convective and nonconvective rain
Surface fluxes are calculated within the model using bulk formulas (BULK_FLUXES option). Evaporation is calculated in the model and saved as output variable.
Brine input
Brine input in the model is introduced as salinity point source in the HFZ port channel.
Position of the source is at the land/sea boundary (coordinates i=203, j=158).
Input flux equals to 0.5 m3/s with brine salinity of 60 psu.
Salinity input is equally distributed between levels 3, 4 and 5.
Available scenarios have constant salinity input. Timedependant salinity release was tested.
ROMS scenarios
ROMS results are organized into ROMS scenarios. Each scenario refers to 24 hours period of model output. Additional 5 days scenario named "TOTAL" are given for overview consisting from joined 5 sequential model outputs.
ROMS scenario displays following ocean variables: temperature, salinity, 3D currents, salinity increase, sea surface height, timeseries of evaporation, input of brine and vertical averaged salinity at the observational station.
Salinity increase is defined as (salinity  default_salinity)/default_salinity*1000.
MM5 coupling
Each ROMS scenario with surface forcing has corresponding MM5 scenario where atmospheric
conditions are displayed for the ROMS domain. The extraction of MM5 data for ROMS domain
can be done automatically by saving MM5 timeseries into the MM5 domain station,
which can be read by a ROMS preprocessing function that interpolates MM5 data
on the ROMS grid and create atmospheric forcing fields in the realtime.
