Solar radiation vs. global radiation

[Jochen]

Dear SWAT users,

I am confused a bit about the term "solar radiation".

In the ArcSWAT manual on p.25 it says:

"The solar radiation data table is used to store the total daily amounts of solar radiation

reaching the ground that are recorded at a specific weather station."

reaching the ground in this case is global radiation (measured by a pyranometer) isn't it? Thats the amount of radiation that reaches the ground...?!

Best regards

Jochen

[Jim Almendinger]

This is outside my expertise, but I presume here "ground" really means the canopy surface, and the radiation reaching the soil surface (which might more commonly be thought of as "ground") has been reduced by LAI.    

I'm not sure I understand your concern here -- is it the use of the word "ground" to describe where solar radiation is measured, or is it because a weather station with a pyranometer is measuring "global radiation" rather than "solar radiation"?  And, if so, what's the difference between the two?  

-- Jim

Dr. James E. Almendinger, Senior Scientist
St. Croix Watershed Research Station
Science Museum of Minnesota
16910  152nd St. N
Marine on St. Croix, MN  55047
tel: 651-433-5953 X 19
fax: 651-433-5924
email: din...@smm.org
web: www.smm.org/SCWRS/

[Kerem Güngör]

Hi Jochen,

I think you can assume that "total global solar radiation" typically measured by weather stations all across the globe as "solar radiation" input in SWAT directly. 

I downloaded data from Global Weather database constructed for SWAT users (http://globalweather.tamu.edu/) for my project. I also obtained measured "total global solar radiation" data from the Turkish meteorology general directorate. Average monthly values of the two data sets agreed pretty well for the same time period.

I hope this input is helpful.

Best,

Kerem 

[Jochen]

Hi Kerem,

thanks for your answer.

So to make it comparable: Global radiation for me covers a spectral range of 200 to 3600 nm

(more or less). So I assume, Turkish meteorological acgency uses comparable pyranometers, do they?

Best regards

Jochen

[Kerem Güngör]

Jochen,

Most probably they do. The stations that measure total global solar radiation have been functional since mid-2000s in Turkey and these are standard automatic weather stations. I do not have the specs of their pyranometers though.