[Ncep.list.emc.monsoondesk] query on GFS product as met input data in WRF

Kate Howard - NOAA Federal kate.howard at noaa.gov
Fri Feb 24 15:26:56 UTC 2017


The GFS product you list does not have a spin-up time. It was already
warmed by prior model runs in production. You could use the f000 file
(first time step) or the analysis file (anl). I'm not exactly sure what the
WRF model prefers. I can't say exactly how many time steps it takes before
the error grows "high"...we normally describe that based on forecast hours.
You can review the performance metrics of the GFS at this webpage:


Of interest to you would be the dieoff curves, which are viewable after
choosing "Anomaly Correlation" on the left. Those plots are based on
forecast hour. An anomaly correlation less than 0.6 is considered low skill.

In the future please contact our Monsoon Desk for NCEP model inquires. All
inquires from IITM are coordinated through that desk. I have cc'd our
Monsoon Desk contact (Partha Bhattacharjee) to let him know of your inquiry.

Kate Howard
Global Forecast System (GFS)

On Fri, Feb 24, 2017 at 1:19 AM, Sujit Maji <sujit.cat at tropmet.res.in>

> Dear Sir/Madam,
> I want to use GFS product gfs.tCCz.pgrb2.0p50.fFFF (from
> http://www.nco.ncep.noaa.gov/pmb/products/gfs/) as meteorological inpout
> to  forecasting system using WRF-Chem. I have following queries.
>  Is the above mentioned GFS output product contain any spin-up time ?
>  Can I use GFS output data from time 000 (gfs.tCCz.pgrb2.0p50.f000) as
> input to WRF ?
>  or, I have to use data after the the spin-up time (e.g. if spin-up time
> is 24 hrs, then i will use data from gfs.tCCz.pgrb2.0p50.f024).
>  How many time steps of this data product is useful before the error grows
> high ?
> Thanks and regards,
> Sujit Maji
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