Generating shapiro.gr3
A Laplacian viscosity in the form of Shapiro filter (Shapiro, 1970; Zhang et al. 2016) was locally applied near steep slopes where the spurious modes further exacerbated the pressure gradient errors. The specified Shapiro filter strength (γ; non-dimensional; Zhang et al. 2016) was based on the local bathymetric slopes (α; non-dimensional) as γ=0.5 tanh(α/α_0 ), where α_0 is a reference slope, chosen to be 0.5 in the current case. This led to a maximum filter strength of 0.5 for large bathymetric slopes. Additionally, γ=0.2 is specified inside the Delaware Bay and γ=0.5 inside the Chesapeake Bay.
In the latest ECGC (east coast and gulf coast) setup that covers all watersheds (<10 m, MSL), the entire coastal regions (specified by *.reg files) are assigned large filter strenghth (0.2-0.5).
A group of scripts are provided under this folder (Shapiro/) for automatically generating shapiro.gr3. You can put the folder into your run directory, then do:
[your_run_dir]$ cd Shapiro/
[your_run_dir/Shapiro]$ ./auto.pl
This will make a shapiro.gr3 and save a copy in your run directory. You can read "auto.pl" to see what steps are involved.
References
Shapiro, R., 1970. Smoothing, filtering, and boundary effects. Reviews of geophysics, 8(2), pp.359-387.
Zhang, Y.J., Ye, F., Stanev, E. V, Grashorn, S., 2016. Seamless cross-scale modelling with SCHISM. Ocean Model. 102, 64-81.
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