Is it possible to run WXGEN weather generator externally to SWAT?

[Steven Jepsen]

All,

I am currently using the internal WXGEN weather generator in SWAT to create time-series forcings for solar, wind, and relative humidity. This is done "dynamically" during a SWAT run. This seems "black boxy" (sp?) to me in that I am not able to examine the time-series generated by WXGEN. Moreover, the WXGEN-simulated values for wind and relative humidity are not available in any form of SWAT output.

So, what I think I'd like to do is run the WXGEN weather generator independently of SWAT, to obtain the synthetic time-series of solar, wind, and relative humidity. I would probably need to provide the reference weather stations (e.g., those selected in ArcSWAT), and possibly the latitude and longitudes of gauge locations. I would then like to examine and possibly modify the time series generated by WXGEN, then input those to back into SWAT as the *.SLR, *.WND, and *.HMD text files.

The reason that I'd like to do this is that I am trying to produce long-term meteorological data series that exactly repeats itself each year, for use in long-term spin-up analysis of forests. I've done this so far for temperature and precipitation. I think I can do it using outputs of solar from SWAT (if those are indeed the downwelling values, or if I can get albedo outputs). I can't do this for wind speed or relative humidity because these generated values are not available as outputs from SWAT.

In summary, my question is: is it possible to run the WXGEN weather generator independently of SWAT, to obtain the synthetic time-series of solar, wind, and relative humidity?

Is the SWAT Weather Database tool supposed to do this? (https://swat.tamu.edu/software/links/). I played around with it, but couldn't get anything out of it resembling what I'm looking for.

Thanks,

Steve

[Juan Sebastián Acero Triana]

As far as I know that is not possible. However, you can modify SWAT's code to print the variables that you need.

Cheers,

Juan Sebastian Acero Triana

Graduate Research Assistant

Soil and Water Resources Engineering

Agricultural and Biological Engineering

University of Illinois at Urbana-Champaign

[Baffaut, Claire]

You could use the stand-alone WXGN, which you can find at https://epicapex.tamu.edu/model-executables/ in the supporting tools section. This is the weather generator used in EPIC and APEX. I don’t know for sure what differences there are with the weather generator used by SWAT but they are very close.

 

Claire Baffaut

Tel: (573) 882-1251 (New as of May 2018!)

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[Steven Jepsen]

Claire,

Thank you for posting this information, which I just now read (I need to enable email notifications...). I was not aware of this stand-alone version of WGENX.

Steve

[simon muthee]

At Claire Baffaut,  Could you please share a manual for using the stand alone -WXGN V.1101