.. _trouble-shooting:

*******************
 Trouble-shooting
*******************

If you encounter problems getting LANL POP to run, a list of known bugs
is maintained at the LANL POP website and the user should check there
before contacting the developers. In addition, there are other common
sources of error listed below with suggestions for avoiding such
problems.

Users who have difficulty getting POP2 to run after reading the
this manual and the `CESM User's Guide <../../../cesm/index.html>`__
should send questions to cesm-help@cgd.ucar.edu

Timestep stability criteria
---------------------------

As part of the POP diagnostics, the Courant number for various processes
can be output. The Courant number should always be less than one and
often should be kept under 0.5 for stability. If such a CFL condition is
exceeded, reducing the timestep may be a solution. However, it should be
noted that often other underlying problems may be causing these limits
to be exceeded (e.g. unrealistically high velocities) and reducing the
timestep will only prolong the agony. In such cases, the particular CFL
condition that is violated can help pinpoint the source of the problem.

Checking the global energy and work balances
---------------------------------------------

Getting the right combination of mixing options
------------------------------------------------

Getting the right combination of forcing options
-------------------------------------------------

Properly normalizing input salinity values
-------------------------------------------

The units for salinity in the model are g/g. Care must be taken to
renormalize salinity data, which is often in g/kg.