WRF Restart Behavior: Output Time at Restart vs Next Time Step

[Naser]

Hello everyone,

I have a question regarding the restart option in the WRF namelist.

Suppose I run the model hourly for 2 days, from:
2024-01-01 00:00 to 2024-01-03 00:00

The model runs successfully for the first day, and I want to restart from:
wrfrst_d01_2024-01-02_00:00:00

In my first run, I already have:
wrfout_d01_2024-01-02_00:00:00

When I restart the model using wrf.exe, sometimes it correctly produces:
wrfout_d01_2024-01-02_01:00:00

However, in some cases, it unexpectedly generates:
wrfout_d01_2024-01-02_00:00:00 again before continuing.

My question is:

When restarting from a specific time, should WRF generate output starting from the restart time itself, or from the next time step (e.g., +1 hour)?

I hope my question is clear, and I would appreciate any clarification.

Thank you.

Naser

 

[Ming Chen]

Naser,

There are two namelist options you can set to determine whether you want output at the restart time:


write_hist_at_0h_rst = .false., ! whether to output history file at the start of restart run


write_restart_at_0h = .false., ! whether to output restart file at the start of restart run

 

[Naser]

Dear Chen,
Thank you for your answer.

I have a question regarding the write_restart_at_0h option.
If a restart file (wrfrst) at a specific time already exists, I am wondering why it is necessary to generate it again by activating this option.
According to the README.namelist, this option is related to ensemble breeding. However, I am having difficulty understanding the reasoning behind this.

Thank you.
Naser

 

[Ming Chen]

Hi Naser,
We once had some issues when restart interval is changed (i.e., in the restart run, it is different to that in the initial run). This option was added to address the issue back then. You are right that it is not necessary to turn on this option.

 

[Naser]

Hello Dear Chen,
Thank you for your answer. It’s much clearer to me now.
Best,
Naser