NR-LITE2 Net Radiometer
12
sensitivity at an angle of incidence of 90 degrees (radiation passing over the
sensor surface). At any angle between 0 and 90 degrees the sensitivity should
be proportional to the cosine of the angle of incidence.
shows the behavior of a typical net radiometer. The vertical axis
shows the deviation from ideal behavior, expressed in percentage deviation
from the ideal value.
FIGURE 8-2. Cosine response of a typical net radiometer
8.4 Sensitivity to Wind Speed
The calibration of the NR-LITE2 is carried out at zero wind speed. At any
other wind speed, the sensitivity will decrease. It has been shown that this
decrease in sensitivity is less than 1% of reading per meter per second wind
speed, and the effect is essentially independent of the radiation level.
Net radiation readings can be corrected for wind speed sensitivity using the
following equation, which was developed by Jerry Brotzge at the Oklahoma
Climate Survey:
Wind Sensitivity equation for the NR-LITE2:
Rn,cor = Rn,obs
U < 5 m s
-1
Rn,cor = Rn,obs
∗
(1.0 + A
×
(U
─
5.0))
U > 5 m s
-1
Where,
Rn,cor = Net radiation corrected for wind speed
Rn,obs = Net radiation not corrected for wind speed
U = Horizontal wind speed in m s
-1
A = empirical constant derived from data = 0.021286
9. Maintenance and Troubleshooting
All factory repairs and recalibrations require a returned material
authorization (RMA) and completion of the “Declaration of
Hazardous Material and Decontamination” form. Refer to the
page at the beginning of this manual for more
information.
NOTE
