NR01 Four-Component Net Radiation Sensor
2
4. Overview
The NR01 is a four-component net-radiometer consisting of two pyranometers
of type SR01, two pyrgeometers of type IR01, a heater, and a PT100
temperature sensor. The pyranometer measures solar radiation (short wave or
SW) and the pyrgeometer measures far infrared (long wave or LW) radiation.
LW radiation is mainly present in the 4500 to 50000 nm region, while SW is
mainly present in the 300 to 3000 nm region (see FIGURE
).
FIGURE 4-1. Atmospheric Radiation as a Function of Wavelength
The PT100 temperature sensor is included in the connection body of the
pyrgeometers for calculation of the sky and surface temperature. The heater is
included in the pyrgeometers’ connection body, and is used to prevent dew.
Measurement of the separate components of the net radiation is useful because
it:
•
Enhances accuracy by having separately calibrated instruments
(similar accuracy cannot be attained with sensors with single outputs
or dual outputs). Single-output or dual-output instruments will always
suffer from instrument asymmetry or from errors due to sensitivity
differences for LW and SW radiation.
•
Provides more detailed information than sensors with single or dual
outputs (e.g., albedo of the ground, cloud condition).
•
Allows more thorough quality assurance of the instrument data
(compared to sensors with single or dual outputs). Quality assurance
with four-component radiometers is done by analyzing trends in SW
in
absolute signal, SW albedo, correlation of SW
in
and LW
in
, SW night
time signals, and correlation LW
out
and surface temperature.
LW
SW
