Omega tries to read NTracers from input file

[xylar]

When I try to read in an InitialState stream with the following spec in the omega.yml file:

    InitialState:
      UsePointerFile: false
      Filename: init.nc
      Mode: read
      Precision: double
      Freq: 1
      FreqUnits: OnStartup
      UseStartEnd: false
      Contents:
      - State
      - Base

I'm seeing:

[* error] [IO.cpp:334] PIO error while reading dimension NTracers 
[* error] [IO.cpp:334] PIO error while reading dimension nTracers 
[* warning] [IOStream.cpp:668] Dimension NTracers not found in input stream InitialState

I don't think we will ever expect to have NTracres (or nTracers) as a dimension in a file, right? It is a convenience in code but I don't think we have a capability to write out the tracer array with this dimension. At the very least, we should skip over this dimension without a warning let alone an error if it doesn't exist.

[xylar]

This is not causing any issues, it just seems confusing in the output.

[philipwjones]

@xylar I had to add NTracers because it's used for some of the output variables - I think some of the Aux variables have a tracer index? But I think the proper way to handle dimensions for file reads is not to read in all defined dims but to just read in dimensions from the input file and only print error/warnings if something is missing or of inconsistent length. I'll work on changing that.

[xylar]

Okay, that explanation and also the solution you propose both sound very reasonable.