CNR4 Net Radiometer by Kipp & Zonen

The energy balance between inbound short-wave and long-wave Far Infrared (FIR) radiation and surface-reflected short-wave and long-wave radiation is measured by the CNR4 net radiometer.

The CNR4 net radiometer is made up of a pyranometer pair, one facing upward, the other facing downward, and a pyrgeometer pair in a similar configuration. 

A meniscus dome is present on CNR4’s upper long-wave detector. This ensures that water droplets easily roll off the dome and improves the field of view to nearly 180°, compared with a 150° for a flat window.  For compatibility with every data logger, a Pt-100 and a Thermistor are included as temperature sensors.

To adjust the infrared values for the temperature of the instrument housing, information from the temperature sensor is needed. The design of the extremely low weight and built-in sun cover minimizes the impact of thermal effects on both long-wave and short-wave measurements. For transportation, the mounting rod can be unhooked.

As an expansion of the sun shield, an additional CNF4 ventilation unit with a heater can be installed either when the CNR4 is first built or afterward. This unit’s small size and effective airflow over the domes and windows prevent dew development and the need for frequent cleaning. Frost can be melted with the help of the built-in heater.


Light Weight

The CNR4 is small in size and incorporates a sun cover to lessen the impact of heat on all measures.

Optional Ventilator

To avoid data loss due to precipitation and to lessen the frequency of cleaning, the add-on CNF4 can be incorporated or retrofitted.

180° Field of View

A meniscus dome can be seen on the upper long-wave detector. As a result, water droplets will roll off quickly and the field of view will be improved to approximately 180° from 150° for a flat window.


Technical Attributes

Source: OTT HydroMet - Meteorology

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Non-linearity < 1%
Operating Temperature Range -40 - +176 °F (-40 - +80 °C)
Outputs Analog 4 x separate up/down and LW/SW
Response Time < 18 seconds
Sensitivity 5 - 20 µV/W/m²
Spectral Accuracy 300 - 2800 nm (SW) 4.5 - 42 µm (LW)
Temperature Dependence of Sensitivity < 4% 14 - +104 °F (-10 - +40 °C)

CNR4 Net Radiometer by Kipp & Zonen

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