Specifications

CNR4 Net Radiometer
2.3 Pyrgeometer Specifications
Spectral range:
4.5 μm to 42 μm (50% points)
Sensitivity:
5 to 15 μV/W/m
2
Impedance:
20 Ω to 200 Ω (typically 50)
Response time:
< 18 seconds (95% response)
Non-linearity:
< 1% (-250 to +250 W/m
2
irradiance)
Temperature dependence of
sensitivity:
< 4% (-10° to +40°C)
Tilt error:
< 1% (deviation when tilted at any
angle off horizontal)
Zero offset due to temperature
change:
±4 W/m
2
(5K/hr temperature change)
Field of view
Upper
Lower
180 degrees
150 degrees
Net-irradiance:
-250 to +250 W/m
2
Non-stability:
< 1% (sensitivity change per year)
Window heating offset:
< 6 W/m
2
(1000 W/m
2
solar
irradiance)
Uncertainty in daily total:
< 10% (95% confidence level) indoor
calibration
Typical signal output for
atmospheric application:
±5 mV
Temperature sensors
Thermistor:
10k Ω
Pt-100:
DIN class A
Instrument calibration:
Indoors, side by side against reference
CG(R) 3 pyrgeometer. On request
outdoors, side by side against
reference CG(R) 4 pyrgeometer
2.4 Optional CNF4 Heater/Ventilator
The purpose of the heater/ventilator is to prevent dew deposition on the
pyrgeometer and pyrgeometer window, thus enhancing the measurement
accuracy and reliability. Using the heater/ventilator will have negligible effect
on the pyranometer reading.
Generally, the errors caused by the heater/ventilator will be small relative to the
errors that would have been caused by water deposition.
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