CNR4 Net Radiometer
4
7. Select the measurement and its associated output options.
8. Click
Finish
and save the program. Send the program to the data logger if
the data logger is connected to the computer.
9. If the sensor is connected to the data logger, check the output of the sensor
in the data display in
LoggerNet
,
PC400
,
RTDAQ
, or
PC200W
to make
sure it is making reasonable measurements.
5. Overview
The CNR4 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 short-wave solar radiation, and the
pyrgeometer pair measures long-wave far infrared radiation. The upper long-
wave detector of CNR4 has a meniscus dome to ensure that water droplets roll
off easily while improving the field of view to nearly 180°, compared with a
150° for a flat window. All four 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 thermistor and a Pt-100, are integrated with the
CNR4 body. 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 ensures that the temperatures of the measurement
surfaces are the same and accurately known, improving the quality of the long-
wave measurements. A completion resistor is added in the pig tail end of the
thermistor cable providing an easy interface with data loggers for half-bridge
measurement.
The CNR4 design is light weight and has an integrated solar shield that reduces
thermal effects on both the short-wave and the long-wave measurements. The
cables are made from Santoprene
jacket, which is intended for outdoor use,
and is resistant to a variety of pollutants and UV-radiation. The mounting rod
can be unscrewed for transport.
An optional ventilation unit with a heater, CNF4, is designed as an extension of
the solar shield and can be fitted to the CNR4 or retrofitted later. The
heater/ventilation unit is compact and provides efficient air-flow over the
