Clarification on "gfdda_interval_m" in spectral nudging

[met-sree]

Dear all,

I need a clarification regarding the parameter "gfdda_interval_m". I am running the model with NCEP FNL data (3-hour temporal resolution and 0.25° spatial resolution) for a 10-day simulation.
I want to apply spectral nudging on a daily interval (at each 00 UTC) instead of every 3 hours (which is the temporal resolution of my input data). Is this possible?

Thank you.
Sree

 

[Ming Chen]

Sree,

In this case, please set gfdda_interval_m = 1440.

 

[met-sree]

Dear Ming,
Thank you for your prompt reply. I understand that gfdda_interval_m is often set to match the time interval of the analysis data (GFS). Could you please confirm if this is mandatory? For instance, if my analysis files (metgrid files) have a 3-hour interval, is it acceptable to set gfdda_interval_m to 1440 instead of 180?

Thank you,
Sree

 

[Ming Chen]

Sree,

Thank you for raising this issue. I just double checked the code, and spectral nudging is conducted at the time interval of gfdda_interval_m. Note that your input data for nudging (i.e., wrffdda_d<domain>) should have data at the same time interval.

Hope this is helpful for you. Please let me know if you have more questions.

 

[met-sree]

Dear Ming Chen,
Thank you for your clarification.