The CNR 4 net radiometer measures the energy balance between incoming short-wave and long-wave Far Infrared (FIR) radiation versus surface-reflected short-wave and outgoing long-wave radiation.

The CNR 4 net radiometer consists of a pyranometer pair, one facing upward, the other facing downward, and a pyrgeometer pair in a similar configuration. The pyranometer pair measures the short-wave radiation. And the pyrgeometer pair measures long-wave radiation. The upper long-wave detector of CNR 4 has a meniscus dome. This ensures that water droplets role off easily and improves the field of view to nearly 180°, compared with a 150° for a flat window. All 4 sensors are integrated directly into the instrument body, instead of separate modules mounted onto the housing. But are each calibrated individually for optimal accuracy.

Two temperature sensors, a Pt-100 and Thermistor, are integrated for compatibility with every data logger. The temperature sensor is used to provide information to correct the infrared readings for the temperature of the instrument housing. Care has been taken to place the long-wave sensors close to each other and close to the temperature sensors. This assures that the temperatures of the measurement surfaces are the same and accurately known. Which improves the quality of the long-wave measurements.

Technical Characteristics:

Spectral range: 300 to 2800 (short wave) nm

Spectral range: 4500 to 42000 (long wave) nm

Sensitivity: 5 to 20 µV/W/m²

Temperature dependence of sensitivity (-10 ºC to +40 ºC) : < 4 %

Response time: < 18 s

Non-linearity: < 1 %

Operating temperature: -40 to 80 °C

Ventilation power (of the optional CNF 4 ventilation unit): 10 W