Campbell Scientific NR-LITE2 Net Radiometer - Manual (Page 16)

NR-LITE2 Net Radiometer
Error
Angle of Incidence
FIGURE 5-2. Cosine response of a typical net radiometer
5.4 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
FIGURE 5-3 provides scatter plots showing the wind sensitivity for both the
NR-LITE2 and CNR1 net radiometer models.
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