3 pyrgeometer specifications, Pyrgeometer specifications – Campbell Scientific CNR4 Net Radiometer User Manual

Page 19

CNR4 Net Radiometer

Directional error*:

< 20 W/m

at angle up to 80° with

1000 W/m

Zero offset due to 0 to -200 W/m

IR net irradiance*:

< 15 W/m

Zero offset due to temperature
change*:

< 3 W/m

(5 K/hr temperature change)

< 1 W/m

(with CNF4 installed)

Operating temperature:

–40°C to +80°C

Field of view

Upper detector:

Lower detector:

180°

150° (due to lower solar shield to
prevent illumination at low zenith
angles)

Maximum solar irradiance:

2000 W/m

Expected accuracy for daily totals:

±10 %

Typical signal output for
atmospheric application:

0 to 15 mV

Impedance:

20 to 200 Ω, typically 50 Ω

Detector:

Copper-constantan multi-junction
thermopile

Level accuracy:

1 degree

Irradiance:

0 to 2000 W/m

Spectral selectivity:

< 3% (330 to 1500 nm spectral
interval)

Uncertainty in daily total:

< 5% (95% confidence level)

Instrument calibration:

Indoors. Side by side against reference
CMP3 pyranometer according to ISO
9847:1992 annex A.3.1

6.3 Pyrgeometer Specifications

Spectral range:

4.5 to 42 μm (50% points)

Sensitivity:

5 to 15 μV/W/m

Impedance:

20 to 200 Ω (typically 50 Ω)

Response time:

< 18 seconds (95% response)

Non-linearity:

< 1% (–250 to +250 W/m

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

(5 K/hr temperature change)