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Albedometer CM 7B / CM14

albedometer_cm7b_cm14.jpg (6285 octets)Suitable for measuring net global radiation and/or albedo over many differing types of surface.

CM14 is the high accuracy version of CM7B. CM14 complies with the highest level of the standard ISO 9060,i.e. it has secondary standard classification. CM7B complies with the second highest level, first class.

  • Sensors of equal sensitivity
  • Conical lower screen, preventing illumination of the lower glass dome at sunrise and sunset.

The albedometer CM 7B is constructed around two CM 6B and the CM 14 around two CM 11 sensors. Both are rotationally symmetrical beneath K5 glass domes.

A white screen prevents the body of the albedometer from heating up.

The labedometers are equipped with a rod for attachment to a mast. A drying cartridge keeps the interior free from humidity.

All albedometers are supplied with a calibration certificate.

Generally, CM 14 can be recommended for scientific applications, for which accuracy needs to be according to the highest standards. CM 7B is recommended for routine meteorological applications in which the accuracy is not the most important issue.

There are two operating modes for an albedometer: net global radiation is measured with the sensors connected in anti-series.

Separate recordings of the outputs and a subsequent measurement of the ratio of one output to the other yields the albedo calculation.

An albedometer can be used together with a net-pyrgeometer to establish net-radiation.

Specifications

Model CM 7B CM14
Spectral range 305-2800 nm (50% points) 305-2800 nm (50% points)
Sensibility 4-6 µV/Wm-2 9-15 µV/Wm-2
Impedance 700-1500 ohms 70-100 ohms
Response time 1/e 4s, 99% 24s 1/e 5s, 99% 55s
Non linearity ±0.6% (<1000 W/m2) <1.5% (<1000 W/m2)
Tilt error none < 1.5% at 1000 W/m2
Operating temp. -40 to 80°C -40 to 80°C
Temperature dependence of sensibility ±1% (-10 to 40°C) ±2% (-10 to 40°C)
Maximum irradiace 4000 W/m2 2000 W/m2
Directional error <±10 W/m2 at 1000 W/m2 <±20 W/m2 at 1000 W/m2
Weight, including rod 1.9 kg 1.9 kg
Cable length 10 m 10 m
Required for data acquisition two millivolt channels two millivolt channels
Overall classification ISO secondary standard ISO first class