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SCHISM in SMS

SCHISM Model Overview

SCHISM (Semi-implicit Cross-scale Hydroscience Integrated System Model) is a flexible, open-source modeling system used to simulate a range of hydrodynamic and environmental processes. It is integrated with the Aquaveo Surface-water Modeling System (SMS), supporting 2D and 3D simulations.

Interface Overview

The SCHISM interface within SMS contains these key components:

• Model Control Dialog - Main interface for defining simulation parameters.
• Project Explorer - Organizes model coverages, simulations, and files.
• Map and Mesh Views - Interactive visualization of spatial data and mesh structures.
• Simulation Menu and Toolbar - Tools for creating, linking, running, and managing simulations.

SCHISM Model Control Dialog

The Model Control dialog in SMS organizes simulation setup into four main tabs:

• Sections list – A list of sections that can be turned on or off:
  • CORE – Turn on to make the CORE section visible.
  • OPT – Turn on to make the OPT section visible.
  • SCHOUT – Turn on to make the SCHOUT section visible.
  • OTHER – Turn on to make the OTHER section visible.

CORE

Example of the CORE section in the SCHISM Model Control dialog

This section includes the following options.

• Pre-preprocessing flag (pre) – Pre-processing flag (1 = on; 0 = off). ipre=0: normal run. The pre-processing flag is used for checking integrity of the horizontal grid and some inputs.
• Barotropic flag (ibc) – If ibc=1, a barotropic model is used, and the transport equation may (when ibtp=1) or may not (when ibtp=0) be solved; in the former case, S and T are treated as passive tracers.
• Baroclinic flag (ibtp) – If ibc=0, a baroclinic model is used and regardless of the value for ibtp, the transport equation is solved.
• Total simultion time in days (rnday) – The total simulation time designated in days.
• Time step in seconds (dt) – Time step in seconds. This is the main time step in SCHISM.
• msc2 – Only used if the wave module WWM is included. Represents the spectral resolution used in WWM.
• mdc2 – Only used if the wave module WWM is included. Represent the spectral resolution used in WWM.
• # of tracers for GEN (ntracer_gen) – Sets the number of tracer ‘classes’ for the GEN module.
• # of tracers for AGE (ntracer_age) – Sets the number of tracer ‘classes’ for the AGE module.
• # of tracers for SED3D (sed_class) – Sets the number of tracer ‘classes’ for the SED module.
• # of tracers for EcoSim (eco_class) – Sets the number of tracer ‘classes’ for the EcoSim module.
• Global output step spool (nspool) – Control the global netcdf outputs. Output is done every nspool steps.
• Global stack spool (ihfskip) – Control the global netcdf outputs. A new output stack is opened every ihfskip steps. The code requires that ihfskip is a multiple of nspool.

OPT

Example of the OPT section in the SCHISM Model Control dialog

This section contains the following options:

• Start Year (start_year) –
• Start_Month (start_month) –
• Start Day (start_day) –
• Start Hour (start_hour)
• UTC Start (utc_start) –
• Cordinate frame flag (ics) – If set to "1", Cartesian coordinates are used; if set to "2", both hgrid.ll and hgrid.gr3 use degrees latitude/longitude.
• Centers of projection used to convert lon to Cartesian coordinates (sfea0) –
• Centers of projection used to convert lat to Cartesian coordiantes (slam0) –
• Hotstart option (ihot) –
• Ramp-up period in days for B.C. (dramp) –
• Bottom friction option (nchi) –
• Drag coefficient dataset –
  • Select... –
• Coriolis option (ncor) –
• Coriolis parameter (coricoef) –
• Atmos. option (nws) –
• Heat budget model option (ihconsv) –
• Evaporation and precipitation model (isconsv) –
• Turbulence closure (itur) –
• dfv0 –
• dfh0 –
• Advanced –

SCHOUT

Example of the SCHOUT section in the SCHISM Model Control dialog

• Main switch to turn on/off retcdf output (nc_out)
• UGRID option for _3D_outputs under scribed IO (iof_ugrid)
• Option for hotstart outputs (nhot)
• Steps to output *_hotstart (nhot_write)
• Station output option (out_sta)
• Output skip (nspool_sta)
• Global output options (of_hydro)
  • Edit Table...

OTHER Tab

Example of the OTHER section in the SCHISM Model Control dialog

• Model executable
  • "OLDIO PREC_EVAP TVD-VL"
• Cut-off depth for applying tidal potential
• ivcor
• z levels - Control gradient steepness for stability.
  • Edit Table...
• hc
• theta_b
• theta_f
• S levels
  • Edit Table...
• Number of processes

Coverages and Arc Properties

Coverages define geographic features, such as boundaries and forcing conditions. There are two official types of coverages in SCHISM. These define different spatial and boundary configurations.

• Boundary Conditions
• Upwind Solver Coverage

Boundary Conditions Coverage

This coverage is used to specify boundary-related input data for the simulation. It includes settings for external forcing, discharge, and meteorological conditions.

• Open Boundary: Designates boundaries with external forcing (e.g., tides).
• River Inflow: Assigns river discharge to specified boundary arcs.
• Meteorological Forcing: Enables surface forcing from wind or heat fluxes.
• Land Boundaries - Represent no-flow or wall-type boundaries.
• Tidal/Stage Boundaries - Input water level conditions (e.g., time series, harmonic constituents).
• Flow Boundaries - Set discharge inflows/outflows.
• Scalar Boundaries - Input scalar values (salinity, temperature).

Each boundary condition allows for specific input fields such as time series assignment, units, and reference elevation.

Arc Properties

Example of the SCHISM Arc Properties dialog

Arc properties specify flow and connection rules for arcs within SCHISM coverages. Each arc within a boundary condition coverage has properties:

• Boundary Type: Defines if the arc is an inflow, outflow, or internal open boundary.
• Flow Rate: Sets a fixed or time-varying inflow rate.
• Elevation Constraint: Applies elevation-based rules to arc segments.
• Arc Type - Defines arc behavior (land, tidal, flow, scalar).
• Input Values - Define constant or time-series input values for elevation, discharge, etc.

Simulation Menu

Menu Controls

SCHISM Simulation Menu Options

Menu Option	Description
New Simulation	Initializes a new SCHISM simulation item.
Load Simulation	Opens a pre-existing SCHISM simulation.
Delete Simulation	Removes the selected simulation from the project.
Link Coverage	Associates map coverages (e.g., boundary, materials) with the simulation.
Run Simulation	Executes the simulation using defined model parameters.
Export Files	Writes all SCHISM input files needed for a run.
Simulation Properties	Opens the Model Control dialog for configuration.
Save Simulation	Saves current settings and configuration.

Resources

• SCHISM Manual