Dear Zoltan,

thanks a lot for solving this mystery!
You are absolutely right, the figures are for daytime only!
Day length is also provided in the MS-Excel version.

So, just for the records:
Converting MT-Clim generated Downward Shortwave Radiation (W m-2;
acronym in the table: Srad) into average (shortwave) solar radiation
data (Rs; MJ m-2 d-1) the following equation applies:

Rs = Srad * daylength / 1,000,000


Thanks to Mr. Jolly for programming MT-Clim for Excel and sharing it
with the community!

Best regards,
Rolf


> -----Original Message-----
> From: DSSAT - Crop Models and Applications
[mailto:[log in to unmask]]
> On Behalf Of Zoltan BARCZA
> Sent: Tuesday, July 06, 2010 20:23
> To: [log in to unmask]
> Subject: Re: solar radiation prediction with MT-CLIM
>
> Dear Rolf,
>
> MT-Clim provides daytime (i.e. from sunrise to sunset) average solar
> radiation. Daylength (in seconds) is also provided by MTClim (at least
> by the MS-DOS version, I am not familiar with the Excel version), so
you
> may use that to estimate daily sums.
>
> Comparing with our measurements in Hungary the agreement between
> measured and observed data was quite good (i.e. bias-free).
>
> I hope this helps.
>
> Kind regards,
> Zoltan
>
> Sommer, Rolf (ICARDA) wrote:
> > Dear all,
> >
> >
> >
> > I am using MT-CLIM for Excel (0.4 beta;
> >
http://www.ntsg.umt.edu/models/bgc/index.php?option=com_weblinks&catid=1
> > 8&Itemid=32) to estimate solar radiation and humidity from daily
Tmax,
> > Tmin and precipitation. (This is based on the improved
Bristow-Campbell
> > model invented by Thornton and Running in 1999.)
> >
> > However, I am getting somewhat confused by the magnitude of the
results
> > produced:
> >
> > MT-CLIM predicted solar radiation in summer often exceeds 500
Watt/m2
> > (daily average ...I assume...), i.e. 40 MJ/m2/day, whereas
corresponding
> > observed data never surpass 31 MJ/m2/day.
> >
> > Same problem (much too high predicted solar radiation) with the
default
> > data set that is included in the Excel version of the model, meaning
> > that the problem does not lie in my data, but in my apparently
limited
> > ability to make sense out of the results.
> >
> > Anybody who could solve this mystery?
> >
> >
> >
> > Best regards,
> >
> > Rolf
> >
> > ==============================================
> >
> > Dr. Rolf Sommer
> >
> > Soil Fertility and Agro-Ecosystem Modeling
> >
> > International Center for Agricultural Research
> >
> > in the Dry Areas (ICARDA)
> >
> > www.ICARDA.org
> >
> > P.O. Box 5466, Aleppo, Syria
> >
> > Tel 00963 21 2691 2545
> >
> > P Help save paper - do you really need to print this email?
> >
> > ==============================================
> >
> >
> >
>
> --
> ///////////////////////////////////////////////////////////////
> dr. Zoltan BARCZA            E-mail: [log in to unmask]
> Department of Meteorology       Web: http://bzoli.web.elte.hu
> Eotvos Lorand University      Phone: (+36 1) 372-2500/6603
> Budapest, 1518 P.O.Box 32       Fax: (+36 1) 372-2904
> H U N G A R Y
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