Dear John,
thank you for the fast reply!
We have no problems producing data with stochastic weather generators
(we are using indeed LARS WG and also Weatherman). However, for some of
our - rather remote - sites, only precipitation, Tmin and Tmax are
available. Therefore I got interested in the improved Bristow-Campbell
model mentioned below. (I had used the original Bristow-Campbell model
before, with some success.)
I think the solution of my problem lies in what MT-CLIM software indeed
means by 'Downward Shortwave Radiation (W/m^2)'.
Hope somebody knows this...
Regards,
Rolf
From: John R. Porter [mailto:[log in to unmask]]
Sent: Tuesday, July 06, 2010 15:53
To: Sommer, Rolf (ICARDA); [log in to unmask]
Subject: Re: solar radiation prediction with MT-CLIM
dear Rolf
Is this PAR or total short wave? High for both I think. What does a
stochastic generator say - ie LARS WG??
John R Porter
Professor Dr John R Porter
Department of Agriculture and Ecology
Faculty of Life Sciences
University of Copenhagen
Hoejbakkegaard Alle 9
2630 Taastrup DENMARK
Omnes vulnerant, ultima necat...tempus fugit
email: [log in to unmask]
vox: +45 3533 3377/3375
mobil: +45 2917 7181
>>> "Sommer, Rolf (ICARDA)" <[log in to unmask]> 06/07/2010 14:40 >>>
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
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