Screening for unphysical currents and density in diag.F

[arango]

I added the capability to screen for large and unphysical values for ocean currents and density anomaly in diagnostics file diag.F. Two new variables were added to mod_scalars.F:

        real(r8) :: max_speed = 20.0_r8         ! m/s
        real(r8) :: max_rho = 200.0_r8          ! kg/m3

containing the threshold values that will trigger the model to stop (exit_flag=1) because of blowing-up. It will stop execution before of filling output restart file with NaN.

Recall that the routine diag is called once per baroclinic time-step if ninfo=1. However if the model blow-ups in the barotropic time step loop (step2d), you will still get a lot of NaN.

Many thanks to Richard Schmalz for suggesting this capability.