Use invariant.nc as input to replace init.nc, when generating lbc files

[chunhuazhou]

When generating MPAS lbc files, the default input file is init.nc. However if the lbc tasks are run at different cycles from the ic task cycles, we don't want to add an unnecessary ic tasks. To skip this unnecessary ic task, we can use invariant.nc as input when generating the lbc files. The only change is to the streams.init_atmosphere:
from

<streams>
<immutable_stream name="input"
                  type="input"
                  filename_template="init.nc"
                  input_interval="initial_only" />

to

<streams>
<immutable_stream name="input"
                  type="input"
                  filename_template="invariant.nc"
                  input_interval="initial_only" />

I compared the lbc files generated using init.nc vs invariant.nc and they are identical.

Chunhua.Zhou@fe6 rrfsdet_lbc_g01_12.invariant$ for files in lbc.2025-02-1* ; do nccmp -ldfsS $files ../rrfsdet_lbc_g01_12/$files ; done
Files "lbc.2025-02-18_12.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_12.00.00.nc" are identical.
Files "lbc.2025-02-18_13.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_13.00.00.nc" are identical.
Files "lbc.2025-02-18_14.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_14.00.00.nc" are identical.
Files "lbc.2025-02-18_15.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_15.00.00.nc" are identical.
Files "lbc.2025-02-18_16.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_16.00.00.nc" are identical.
Files "lbc.2025-02-18_17.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_17.00.00.nc" are identical.
Files "lbc.2025-02-18_18.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_18.00.00.nc" are identical.
Files "lbc.2025-02-18_19.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_19.00.00.nc" are identical.
Files "lbc.2025-02-18_20.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_20.00.00.nc" are identical.
Files "lbc.2025-02-18_21.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_21.00.00.nc" are identical.
Files "lbc.2025-02-18_22.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_22.00.00.nc" are identical.
Files "lbc.2025-02-18_23.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-18_23.00.00.nc" are identical.
Files "lbc.2025-02-19_00.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-19_00.00.00.nc" are identical.
Files "lbc.2025-02-19_01.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-19_01.00.00.nc" are identical.
Files "lbc.2025-02-19_02.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-19_02.00.00.nc" are identical.
Files "lbc.2025-02-19_03.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-19_03.00.00.nc" are identical.
Files "lbc.2025-02-19_04.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-19_04.00.00.nc" are identical.
Files "lbc.2025-02-19_05.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-19_05.00.00.nc" are identical.
Files "lbc.2025-02-19_06.00.00.nc" and "../rrfsdet_lbc_g01_12/lbc.2025-02-19_06.00.00.nc" are identical.

[guoqing-noaa]

@chunhuazhou
Thanks a lot for the test! This is great! It will save us lots of extra work.

[chunhuazhou]

To add more information here, I also compared the lbc metadata from the two methods:

$ nccmp -lmgfsS lbc.2025-02-18_13.00.00.nc ../rrfsdet_lbc_g01_12/lbc.2025-02-18_13.00.00.nc 
DIFFER : VALUES OF GLOBAL ATTRIBUTE : parent_id : a2wx4ma3h6
oz6cdkzg6g
 <> tbbqzcjezs
oz6cdkzg6g

DIFFER : VALUES OF GLOBAL ATTRIBUTE : file_id : 16b8glan4r <> lh0m558dyk