11. Troubleshooting¶

11.1. Code does not Compile or Run¶

Check the ice.log.* or ice.bldlog.* files in the executable directory, or the standard output and error files for information. Also, try the following:

Delete the executable directory and rebuild the model.
Make sure that there is a Macros.< OS > file for your platform. Modify the directory paths for the libraries.
Make sure all paths and file names are set correctly in the scripts.
If changes were made to the ice_domain_size.F90 file in the source code directory, they will be overwritten by the file in input_templates.

11.2. Departure points out of bounds¶

This error is written from ice_transport_remap.F90 when the ice speed is causing parcels of ice to go beyond a grid cell. This is akin to a CFL violation. Generally changing the timestep in env_run.xml with ATM_NCPL will allow the model to proceed. Note this can only be done for hybrid or startup runs. One can try just adjusting the dynamic timestep as described in the next section.

11.3. Negative Ice Area in Horizontal Remapping¶

This error is written from ice_transport_remap.F90 when the ice model is checking for negative ice areas. If it happens well into a model integration, it can be indicative of a CFL violation. The output looks like:

New area < 0, istep = 119588
(my_task,i,j,n) = 4 21 380 1
Old area = 0.960675000975677174E-05
New area = -0.161808948357841311E-06
Net flux = -0.976855895811461324E-05
(shr_sys_abort) ERROR: remap transport: negative area
(shr_sys_abort) WARNING: calling shr_mpi_abort() and stopping
(shr_mpi_abort):remap transport: negative area 0

The dynamics timestep should be reduced to integrate past this problem. In user_nl_cice set

ndtd = 2

and restart the model. When the job completes set the value back to 1.

11.4. Picard convergence error¶

This is an error from the mushy layer thermodynamics ktherm = 2. One can try changing nit_max in the ice_therm_mushy.F90 code, but this does not often help. Most likely this is an indication of a problem in the forcing. Sometimes reducing the overall timestep may help.

11.5. Tsn init problems¶

Sometimes the surface temperature or snow temperature at the beginning of the thermodynamic iteration may become unrealistic. The lower bound on this error is -100C. This either indicates a problem with the CICE initial file or the forcing. Changing the timestep will not help.

11.6. Thermodynamic Iteration Error¶

This error is written from ice_therm_vertical.F90 when the ice model temperature iteration is not converging in the thermodynamics. This is usually a problem with the forcing from the atmosphere or ocean, but sometimes can be indicative of a timestep problem in the ice. Check the forcing files at point i,j first.

Thermo iteration does not converge
istep1, my_task, i, j:

11.7. Conservation Error¶

This error is written from ice_itd.F when the ice model is checking that initial and final values of a conserved field are equal to within a small value. The output looks like:

Conservation error: vice, add_new_ice
11  :  14  185
Initial value =  1362442.600400560
Final value =  1362442.600400561
Difference =  2.328306436538696D-10
(shr_sys_abort) ERROR: ice: Conservation error
(shr_sys_abort) WARNING: calling shr_mpi_abort() and stopping
(shr_mpi_abort):ice: Conservation error  0

Non-conservation can occur if the ice model is receiving very bad forcing, and is not able to deal with it. This has occurred after a CFL violation in the ocean. The timestep in the ocean may be decreased to get around the problem.

11.8. NX does not divide evenly into grid¶

If you modify the number of tasks used by the ice model, the model may stop with this error written to the log file:

'ERROR: NX must divide evenly into grid,100,8'

The number of MPI processors used by the ice model must divide evenly into the grid dimensions. For example, running the ice model with 8 tasks on the gx3v7 grid will result in an error, since 8 does not divide evenly into the 100 longitude points. To fix this error, change the value of $NTASKS for the uncoupled ice model in the main script. In this case, a value of 4 would work, and the task geometry would also have to be changed.

11.9. Enabling the Debugger¶

This section explains how to set some compiler options for debugging. For the coupled model, set DEBUG to TRUE in the env_build.xml script. Before running the model, be sure to delete the object files or a clean build so that the source code will be recompiled. If a core file is created, it will be in the executable directory. Use some debugging tools for your platform to look at the core file. Useful information may also appear in the standard error and output files.