SUBROUTINE DYPGRIN

DYPGRIN reads from file the depths of all model cells and places these in the depth array H. H may be Shapiro filtered NFILTER times to avoid 2$\Delta x$ -noise in the model fields. On the other hand excessive filtering destroys the topography. The maximum depth, DEPMAX, in the model region is computed. This depth may be used to check whether the selected time step is small enough to satisfy the CFL-criterion. Ocean cells with depths less than DEPMIN are defined as land cells. The Coriolis parameter array COR is defined. The masking arrays FSM, DUM and DVM and the model static depths H, HU and HV are computed. The bottom drag coefficients CBC are computed after DEPTH is called to set up the $\sigma$-layer thicknesses. Based on HU and HV the square roots of these arrays are also computed and stored in HUSQR and HVSQR. These roots are applied in the Coriolis term averaging and are introduced to avoid instabilities, see [17].

The subroutine DYPGRIN may have to be modified from one application to another.