Comparing Rsw last night from the Kipp&Zonen, Quantum, and SPN-1 at 7, I notice that the Quantum reads very close to zero, the K&Z read an average of -1.5 W/m^2 (range -3 to 0), and the SPN-1 an average of +4 W/m^2 (range +2 to +7). Apparently, the nighttime error is proportional to the cost of the sensor??
1 Comment
Steve Oncley AUTHOR
Apr 17, 2012Looking at data in 2011 for stn7, and zeroing out negative values from the K&Z, I get:
Rsw.global.spn = 5.3 + 0.966 Rsw.in.kz (all data)
Rsw.global.spn = 1.6 + 0.975 Rsw.in.kz (after removing spn nighttime values)
Rsw.global = 0.4 + 0.887 Rsw.in.kz (all data)
SPN is off by ~3% and Quantum by 11% -- not too great.