Campbell-scientific NR-LITE2 Net Radiometer Manual do Utilizador descarregar pdf (Página 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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Campbell-scientific NR-LITE2 Net Radiometer Manual do Utilizador Página 16