NR01 RA01 manual v1710 6/71
Introduction
NR01 is a market leading 4-component net radiation sensor, mostly used in scientific-
grade energy balance and surface flux studies. It offers 4 separate measurements of
global and reflected solar and downwelling and upwelling longwave radiation, using 2
sensors facing up and 2 facing down. NR01 owes its popularity to its excellent price /
performance ratio. Advantages include its modular design, low weight, ease of levelling,
and low solar offsets in the longwave measurement. The unique capability to heat the
pyrgeometers reduces measurement errors caused by dew deposition.
NR01 measures the 4 separate components of the surface radiation balance: downward
and upward solar and longwave radiation. The solar radiation sensors are called
pyranometers and the longwave sensors are called pyrgeometers. From these 4 separate
components the net radiation is derived. For calculation of sky- and surface
temperatures, it is necessary to compensate for irradiated heat by the pyrgeometers
themselves (Stefan-Boltzmann law). A Pt100 temperature sensor is included in NR01’s
body for that purpose. Sunshine duration may be estimated according to the WMO
approved pyranometric method.
The solar irradiance is measured by pyranometers model SR01, the longwave radiation is
measured by pyrgeometers model IR01.
In order to prevent condensation of water on the pyrgeometer windows the NR01 has
internal heating close to the pyrgeometers. This keeps the instrument above dew point.
As water blocks longwave radiation, heating will improve the reliability of longwave
radiation measurement, in particular at night, when the risk of condensation is highest.
Solar offsets in the longwave radiation measurement are very low. Features like these
have made NR01 net radiometers popular in energy balance and surface flux studies. In
addition, NR01 net radiometer is practical to mount; it is much lighter than competing
models and a 2-axis levelling assembly is included. The levelling assembly fits a 1 inch
NPS tube (the tube’s recommended outer diameter equals 33.4 x 10-3 m). With the NR01
shim, included in NR01’s delivery, a ¾ inch NPS tube may also be used.
Using NR01 net radiometer is easy. It can be connected directly to commonly used data
logging systems. The irradiance levels in W/m2are calculated by dividing the NR01
outputs, small voltages, by the sensitivities. The longwave irradiance should be corrected
using the instrument body temperature. The sensitivities of all sensors are provided with
NR01 on its product certificate.
NR01 net radiometer has a modular design: it is possible to take the instrument apart
and replace or re-calibrate individual sensors. For this reason it is often selected for use
in large monitoring networks.
Suggested use for NR01:
•energy balance studies
•surface flux measurements
•climatological networks
