Frequency of physics output diagnostics

Submitted by mwong on Wed, 03/03/2021 - 19:56
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UFS Weather Model

The physics tendencies under the diagnostic module "gfs_phys" are output at a frequency set by "fhzero" under the &gfs_phys_nml portion of the input.nml namelist. The CCPP documentation suggests that fhzero must be an integer and greater than zero. Does this mean it is not possible to output these physics tendencies at a frequency less than an hour (e.g., every 5 mins)?

Thanks. 

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Submitted by dom.heinzeller on Thu, 03/04/2021 - 22:38

Hi, it's a little more complicated than that, but essentially yes.

fhzero control when diagnostic variables (accumulated values such as buckets) get reset

fdiag in the same file (input.nml) further up controls, together with other parameters, when to write out diagnostics.

If quilting is used (model_configure -> quilting), then fdiag should match the output frequency controlled by nfhout, nfhmax_hf, nfhout_hf.

If quilting is not used, then fdiag should match the values in the diag_table file.

Both ways don't allow you to output at sub-hourly intervals.

However, you can produce output at every time step or so if quilting is used by setting nsout to a value > 0. I am not entirely sure how well this works with diagnostic quantities, because these will get reset/updated based on fdiag and fhzero, but I think for state variables it will work.

Sorry that I can't give you any better answers, the way the output is configured is very complicated and my understanding limited.

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Submitted by mwong on Mon, 03/08/2021 - 17:56

Thanks for the input, Dom. I am working with quilting off because I want the output from gfs_phys to be on the same grid as the variables in fv3_history.nc. I seem to be able to output at every time step by setting output_freq in diag_table to 0 for the state variables, but the gfs_phys variables are only output at the hour, perhaps limited by the values that fdiag is set to (according to your explanation above).

I'll try to work with hourly diagnostics for now. I might return to this if that's not working for me. Thanks.

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