Using a Solar Radiation meter provides Watts/m, I need to convert to MJ/m-hour for my own ETo calculations.
For the life of me I can't figure it out.
Actual results from the WS (in Wpm2)
-1.0 to ~800
Allowed Range of MJ/m-hour
-6.78 to 27.4
How to convert from Wpm2 to MJ/m-hour???
Thanks
Eric Robishaw
* Last updated by: ERobishaw on 9/25/2008 @ 3:02 PM *
Let me direct you to Table 4.1 in the LI200X-L manual, which shows how to translate a pyronometer's average flux value (W m^-2)that typically use an Average instruction in a DataTable, and convert it to Total Flux Density (MJ m^-2) using the Totalize instruction. Though that's typically done on a daily basis, there's no restrictions on using that same scheme for shorter time periods.
One Watt equals one Joule per second.
If the average Watts per meter squared over the course of an hour is 800 then
800 W/m2 = 800 J/m2/Sec
800 J/m2/Sec * 3600 Sec/Hour = 2,880,000 Joules/m2/Hour
2,880,000 Joules/m2/Hour / 1,000,000 = 2.88 MJ/m2/Hour
Note that for this specific case (hourly average to an hourly total)
2.88 MJ/m2/Hour / 800 W/m2 = 0.0036
therefore
800 W/m2 * 0.0036 = 2.88 MJ/m2/Hour
You could just use 0.0036 as a direct multiplier to get from W/m2 to MJ/m2/Hour.
* Last updated by: ChipsNSalsa on 9/25/2008 @ 4:47 PM *