FOR MEASUREMENT OF THE ENERGY BALANCE
One-component and four-component instruments
Reliable all-weather performance
Light weight and robust
Unique ventilation system
Net Radiometers
CNR 4 is a four-component net radiometer for accurate
and reliable measurements and can be used as the
reference instrument for a network of lower performance
net radiometers. There are four separate signal outputs and
the integrated temperature sensors can be used to calculate
the FIR radiation. The screw-in mounting rod, bubble level,
and cables with waterproof connectors, make installation
easy. The white sun shield reduces solar heating of the
instrument body.
CNR 4 combines two ISO 9060:2018 spectrally flat Class C
pyranometers for solar radiation with two pyrgeometers for
infrared measurements, all integrated into the instrument
body. The upper pyrgeometer has a silicon meniscus dome
so that water rolls off and the field of view is 180 °. The
design is very light weight and includes a mounting rod as
standard. An optional heated ventilation unit, the CNF 4, is
available to minimise offsets, maximize stability and remove
precipitation.
Introduction
Net radiation is the balance between incoming radiation
from the sun and sky and outgoing radiation from the
ground. Short-wave radiation of 0.3 to 3 µm wavelength
reaches the Earth’s surface, where some is reflected and the
rest of the energy is absorbed by the surface. Incoming
long-wave Far Infrared (FIR) radiation from 4.5 to more than
40 µm is also absorbed by the surface, which heats up and
emits FIR back to the sky.
The four components of net radiation are the incoming and
reflected solar radiation, from which the Albedo can be
calculated; and the downward and upward infrared
radiation. These parameters can be measured using a pair of
pyranometers and a pair of pyrgeometers, but more
commonly a net radiometer is used that conveniently
combines four sensors into one compact instrument
.
The simplest type of net radiometer uses a single sensor to
measure the sum of the four net radiation components. This type
of instrument is sometimes referred to as a net pyrradiometer.
NR Lite2 is a single-component net radiometer widely used
in agriculture and hydrology. The thermopile detector is
fitted with black PTFE coated conical absorbers on both
sides that have a very wide spectral response from the
ultraviolet (UV) to the far infrared (FIR). The signal output is
the difference between the sun and sky radiation and the
ground radiation and can be positive or negative, depending
upon the conditions.
There is an integral mounting rod for fitting to masts and
poles, a bubble level, 15 m long signal cable, and a stick to
prevent birds settling on the instrument. The single output
means that the short-wave and long-wave components and the
upwards and downwards components cannot be separated.
For this, use our four-component CNR 4 net radiometer.
Applications
T
he main applications for net radiometers are in
agro-meteorology, in particular for the study of evapo-
transpiration and in climatology, meteorology and hydrology
for the measurement of the radiation balance. Monitoring
over glaciers and ice fields is of particular interest to global
warming studies. Net radiometers are often used in
conjunction with a small automatic weather station and
need to be easily portable
.
Choice of Net Radiometer
Kipp & Zonen offers a range of robust, lightweight, net
radiometers that do not require power to operate. A
mounting rod, bubble level and calibration certificate are
always included.
NR Lite2 has a single output for total net radiation. CNR 4
measures all four components separately. Whatever the
application, Kipp & Zonen can supply a suitable net radiometer.