Description

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. Each sensor is calibrated individually for optimal accuracy.

Two temperature sensors, a PT100 and Thermistor, are integrated and used to provide information to correct the pygeometer’s 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. The accuracy of both sensors is the same and selection depends on which will connect to the data logger or data acquisition system.

The CNR 4 has 2 8-pin connector ports. The connector with the 4 sensor outputs is indicated with an S, the temperature connector is indicated with a T. Both ports have 8 pins but the temperature connector only uses 6, two for the thermistor and four for the 4-wire PT100 outputs.

Diagram

Specification

To improve the measurement accuracy of the CNR4, a CNF4 ventilation unit can be fitted. The CNF4 provides a clean air flow over all four of the CNR4 radiometer domes and windows and it can be used outdoors under all weather conditions. A built-in heater keeps the air just above ambient temperature which helps disperse precipitation and melt frost, or even melt snow and ice in cold climates.