Campbell Scientific NR01 Net Radiometer - Manual (Page 7)

NR01 Four-Component Net Radiation Sensor
The NR01 is supplied with four separate instrument sensitivities. As a brief
explanation, to calculate the radiation level, the sensor output voltage, U, must
be divided by the sensor sensitivity; a constant, E, that is supplied with each
individual instrument. For example:
Φ = SW
in
= U
pyrano, up
/ E
pyrano, up
More information can be found in the chapter on instrument performance.
The NR01 is a passive sensor, and does not need any
power. The NR01 pyrgeometer can, however, be
heated to prevent dew-deposition. WARNING
Putting more than 12 Volt across the NR01 sensor
wiring can permanently damage the sensor.
2. Measurement Principle
The following chapters explain the measurement principles of the NR01.
Pyranometers and pyrgeometers are treated in different paragraphs. The last
section is about expected measurement results.
2.1 General
In its most common application, the NR01 measures net-radiation. The four
components of net radiation are measured and the net radiation is calculated:
The temperature (T
pyrgeo
) for the following formula is in Kelvin.
If the temperature is measured in degrees Celsius, add 273.15 to
the T
pyrgeo
value.
NOTE
SW
in
= U
pyrano, up
/ E
pyrano, up
2.1-1
SW
out
= U
pyrano, down
/ E
pyrano, down
2.1-2
LW
in
= (U
pyrgeo, up
/ E
pyrgeo, up
) + 5.67.10 -8 (T
pyrgeo
) 4 2.1-3
LW
out
= (U
pyrgeo, down
/ E
pyrgeo, down
) + 5.67.10
-8
(T
pyrgeo
)
4
2.1-4
NOTE: in the LW
net
the instrument temperature is cancelled:
LW
net
= U
pyrgeo, up
/ E
pyrgeo, up
- U
pyrgeo, down
/ E
pyrgeo, down
2.1-5
SW
net
= U
pyrano, up
/ E
pyrano, up
- U
pyrano, down
/ E
pyrano, down
2.1-6
NR = SW
net
+ LW
net
2.1-7
Special parameters that could be deducted:
SW albedo = SW
in
/ SW
out
2.1-8
3