DNI in solar tower power

I want to ask about the design point  DNI  how can i find the value of this. 
SAM default put it 950 W/m^2 but some  the articles said  for Example 2100 KWh/m^2/year  how can we converte this to put it  in SAM program ( in design  point DNI) .
could you give  mr an example please .

or when I go to Data viewer  I found the Beam irradiance of the location that I want to do the simulation about it. is the value of the irradiance that found it in the Data viewer enaugh to know the DNI that we want to put it in SAM program or there is another method to do that.
I look forward to receiving positive feedback soon.
Sincerely,

Hi,

Please see the "Solar Multiple" topic in SAM's Help system under "CSP Parabolic Trough" for some suggestions for choosing a reference DNI value.

Best regards,
Paul.