Typical Parameter Selections

Parameter selections concern the model parameter choices one must make when setting up and running simulations. ADCIRC and the coupled ADCRC+SWAN model have a large number of user-controllable parameters. Some parameters represent a balance in model accuracy vs. stability, like enabling vs. disabling advection via NOLICA and NOLICAT. Others balance accuracy vs. run time, like the implicit vs. lumped explicit GWCE formulation via IM (this also affects stability). Meanwhile some parameters represent values for which the true “best” choice is case-dependent or the subject of ongoing research, like controls affecting drag formulations at the sea surface and sea floor. This page is meant to provide users with example model formulations used by experienced ADCIRCers, and to provide a venue for discussion of parameter selection.

In Storm Surge

The following table presents a variety of parameters as used in storm surge modeling by various groups. Parameters in this table cover a range of model setup choices, and include parameterizations built for forecasting-focused simulations, storm hazard-focused simulations, and hindcast-focused simulations. Note that in all cases, nodal attributes Manning’s n at sea floor and surface directional effective roughness length are in use.

Storm Surge Parameter Selections

Region	Mesh	np	GWCE Formulation	Wind Drag Law	Upper Wind Drag Limit	Min Bottom Drag Coef	Advective Terms	Steric	Vert. Datum	ESL	ESL Node Count	time step	h0	velmin	tidal constituents	convcr	SWAN time step	SWAN MXITNS	SWAN NPNTS
Louisiana	LA_v17a-WithUpperAtch_chk.grd	1593521	implicit	Powell	0.002	0.0	off	0.228184	navd	0.05	all	1.0	0.1	0.01	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-07	1200	20	95
Texas	tx2008_r35h.grd	3352598	implicit	Garratt	0.002	0.0	off	0.276300	navd?	none	none	1.0	0.1	0.01	m2,s2,n2,k1,k2,o1,q1	1.00E-07	1200	20	95
National	hsofs.14	1813443	implicit or explicit	Garratt	0.0028	0.0025	off	none	msl	none	none	2.0	0.05	0.05	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-07	1200	20	95
National (Drag Experiment)	hsofs.14	1813443	explicit	Garratt	0.002	0.0	off	none	msl	none	none	2.0	0.05	0.05	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-07	1200	20	95
MS/AL and FL Panhandle	NGOM_RT_v18j_chk.grd	2051346	implicit	Powell	0.002	0.0	off	0.230000	navd	0.02	all	1.0	0.1	0.01	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-07	1200	20	95
North Carolina (low res)	nc_inundation_v6d_rivers_msl.grd	295328	explicit	Garratt	0.0035	0.003	on	none	msl	none	none	0.5	0.02	0.02	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-10	1200	20	95
North Carolina (high res)	nc_inundation_v9.99a_w_rivers.grd	624782	explicit	Garratt	0.0028	0.003	on	0.0	msl	none	none	0.5	0.1	0.01	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-10	1200	20	95
Delmarva	FEMA_R3_20110303_MSL.grd	1875689	explicit	Garratt	0.0035	0.003	on	none	msl	none	none	1.0	0.1	0.01	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-07	1200	20	95
NY/NJ	FEMA_R2_norivers_gcs_mNAVD.grd	604790	implicit	Garratt	0.0035	0.003	on	none	msl	none	none	1.0	0.1	0.01	m2,s2,n2,k1,k2,o1,q1	1.00E-08	1200	10	95
New England	NAC2014_R01_ClosedRivers.grd	3110470	implicit	Powell	0.002	0.0	off	0.10900	msl	none	none	?	0.1	0.01	m2,s2,n2,k1,k2,o1,p1,q1	1.00E-07	n/a	n/a	n/a

In Tides

Many tide models are configured the same as the above surge models, although some users have reported poor tide performance if the minimum bottom drag coefficient is set to zero. One explanation of this difference in behavior is that the bottom drag differs between tidal and wind-driven flows. The vertical variation in horizontal flow is not known in a 2D model, making prescription of bottom drag ambiguous because the near-bottom velocity is unknown.

Discouraged Parameter Selections

As ADCIRC has grown, some features have been improved upon, making others obsolete. This section addresses such parameters and values.

NWS=19 should not be used, as NWS=20 has the same input requirements but is considered to produce a better, more physically representative wind field. See NWS Parameter and Generalized Asymmetric Holland Model for more details.