MaxDensity blowup

[AMIRHOSSEIN]

Hi everybody
my grid file has 30 vertical layers, but by changing the boundary and time, I could not prevent the model error(in 30 vertical layers), but considering 16 layers (the grid file is the same 30), the model was executed correctly for a year and I do not know where the problem comes from?!
I face this error(MaxDensity)when I use a shorter time step with 30 vertical levels.

[wilkin]

Both your log files show high vertical velocity values in the vicinity of point (060,092,30) ...

roms.log:

23871 2012-11-25 03:05:00.00 5.381065E-03 1.213158E+04 1.213159E+04 1.738389E+14
(060,092,30) 5.036566E-02 3.810904E-02 7.289321E+01 3.587618E+00
23872 2012-11-25 03:06:40.00 5.381077E-03 1.213159E+04 1.213160E+04 1.738387E+14
(060,092,30) 5.536307E-02 4.062285E-02 8.834156E+01 3.923022E+00
23873 2012-11-25 03:08:20.00 5.380875E-03 1.213160E+04 1.213161E+04 1.738384E+14
(060,092,30) 0.000000E+00 1.370364E-02 1.049997E+02 2.649902E+00
23874 2012-11-25 03:10:00.00 5.380806E-03 1.213161E+04 1.213162E+04 1.738382E+14
(060,093,30) 0.000000E+00 6.282926E-04 3.423901E+01 2.649572E+00

roms-shorter.log

37873 2012-11-23 19:13:00.00 7.071512E-03 1.213979E+04 1.213980E+04 1.736103E+14
(060,092,30) 3.659442E-02 3.070058E-02 6.380443E+01 4.513787E+00
37874 2012-11-23 19:14:00.00 7.072364E-03 1.213980E+04 1.213981E+04 1.736101E+14
(060,092,30) 3.718743E-02 3.103912E-02 6.717696E+01 4.559514E+00
Found Error: 01 Line: 315 Source: ROMS/Nonlinear/main3d.F
Found Error: 01 Line: 303 Source: ROMS/Drivers/nl_ocean.h, ROMS_run

Blowing-up: Saving latest model state into RESTART file
REASON: MaxDensity = 3.6E+02

WRT_RST - wrote re-start fields (Index=1,1) in record = 3

It is possible that your bathymetry is just too steep or variable there and large vertical velocities (perhaps due to a strong horizontal flow encountering steep bathymetry) are triggering instability in the advection scheme that leads to over/undershooting and eventually crazy density values.

Note that the solution at blow-up was written into record 3 of the history file - see text highlighted in blue above. View this to see if extreme values are occurring near i=60 j=92.

[AMIRHOSSEIN]

Hi dear Wilkin,

I checked record 3 of the history file and as you said the problem was in the bathymetry then I used romstools for creating grid and tide and run the model and the model run correctly

finally, I checked the zeta parameter in .his file but the Results of zeta were not in the desired range(should be somehow -1.5<zeta<+1.5)

Capture.JPG (38.01 KiB) Viewed 5126 times

Thank you for your patience