Possible to handle hourly restarting with > 1 h LBC files?

[Samuel.Degelia]

Hello, I am wondering if it is possible for MPAS Atmosphere to handle hourly restarting for data assimilation with LBC files only available every 3 hours. I have tried generating hourly LBC files using `config_fg_interval = 3600` (and corresponding values in the lbc stream), but init_atmosphere_model.x crashes as it expects the grib files to also be hourly. If we only generate 3 h LBC files, is it possible to restart the model at a time when LBCs are not available? For example, if we only have LBC files available at 00 and 03 UTC, can we restart at 01 UTC for hourly cycled DA?

If this is not an option, we plan to implement time interpolation of the grib files using wgrib2. This is not necessarily a problem, but we would prefer to do it within the model or inside init_atmosphere_model.x if that is an option.

Thanks,
Sam Degelia

 

[Ming Chen]

Sam,
config_fg_interval must be the same as the temporal resolution of your forcing data. Yes you can restart the model at a time when LBCs are not available. However, if this is for the purpose of cycling, I suppose it wouldn't work. I am not an expert on MPAS-DA, and therefore this is just my personal idea. I will talk to our expert and get back to you.

 

[Samuel.Degelia]

Thank you for the response, Ming. I will wait to hear back from you.

 

[Ming Chen]

Sam,
I talked to our MPAS-JEDI expert. They agree that MPAS-DA only updates meteorological variables at the time of cycling, but it does not modify lateral boundary. Therefore, you cannot do hourly cycled DA based on restart files created at hourly interval.
Hope this is helpful you. Let me know if you have more questions.

 

[Samuel.Degelia]

Ming, thank you again for the update. It is good to know that this likely will not work. We will move forward with performing time interpolation of the grib files to generate hourly LBCs.