Remove atmos_prod f000 rocoto task when OFFSET_START_HOUR is greater than 0

[EricSinsky-NOAA]

What is wrong?

When OFFSET_START_HOUR is greater than 0, the atmos_prod f000 task is still added as a rocoto task. This is an issue because if the OFFSET_START_HOUR is greater than 0, then the atmos_prod f000 task will never be triggered, which results in a stalled atmos_prod task. This may cause downstream tasks to never be triggered, particularly tasks that depend on all lead times to complete for the atmosphere component.

What should have happened?

The atmos_prod f000 task should be removed when OFFSET_START_HOUR is greater than 0.

What machines are impacted?

All or N/A

Steps to reproduce

1. Set REPLAY_ICS to YES.
2. Set OFFSET_START_HOUR to a value greater than 0.
3. Make sure atmos is included as a component.

Additional information

Below is a screenshot of an example of the atmos_prod f000 task not being triggered. In this example, OFFSET_START_HOUR is 3.

Do you have a proposed solution?

One possible solution is to have an FHMIN specifically for the atmosphere, such as FHMIN_ATMOS. It should be noted that the wave component has its own FHMIN, which is called FHMIN_WAV. When OFFSET_START_HOUR is greater than 0, FHMIN_ATMOS should be set to OFFSET_START_HOUR, while the FHMIN for the ocean and ice should be 0.

[EricSinsky-NOAA]

It looks like there is already an FHMIN variable for the atmosphere called FHMIN_GFS. However, it appears FHMIN is being used in the forecast_predet and forecast_postdet scripts. FHMIN is being used for atmosphere, ocean and ice. For the atmosphere-related functions in predet and postdet, I think FHMIN can be replaced with FHMIN_GFS.