[Wrf-users] WRF Seasonal Variations

Kevin Matthew Nuss wrf at nusculus.com
Fri Sep 2 12:21:40 MDT 2011

Hi David,

No, the VEGPARM.TBL parameters get changed frequently (daily I believe or
perhaps with every timestep). The VEGPARM.TBL values represent a range and
get adjust within that range corresponding to the range of values the grid
cell gets from the greenfrac database within WPS, which populates the
GREENFRAC variable with average monthly values. During a run, WRF
interpolates between the 12 monthly values for the current day. But to cause
the updates to happen, you need to use the "sst_update" option in
namelist.input. I believe most of the parameters go up with the exception of
albedo, which goes from max to min as less soil is exposed when greenfrac
goes from min to max. Also, there is a "usemonalb" variable in the
namelist.input file which you might consider using (I don't).

If you turn on "sst_update" you have to re-run real.exe to produce another
input file for wrf.exe. Read the WRF Users Guide about configuring for the
new input files when "sst_update" is used.

Hmm. That was not explained well, but I hope you get the drift of what I was
trying to say. And there is a little more in the User Guide.


On Thu, Sep 1, 2011 at 4:22 PM, Huber, David <dbh409 at ku.edu> wrote:

> Hello,
> If I were to perform a 1-year long simulation in WRF, would how often would
> it change the land cover parameters?  I noticed in VEGPARM.TBL that there
> are only winter and summer values, so does this mean that there is a sudden
> change in vegetation parameters once or possibly twice in a year-long
> simulation, that the vegetation parameters change regularly throughout the
> simulation, or that they stay the same as the initial vegetation parameters?
> Thanks,
> David
> _______________________________________________
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> Wrf-users at ucar.edu
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