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SERVICE
5. SERVICE
This section describes the maintenance of the ATMOS 41W. Troubleshooting solutions and
customer services information are also provided.
5.1 UNINSTALLING
Sometimes the ATMOS 41W must be uninstalled to perform routine maintenance, at the end
of the field season, or to send in for recalibration.
After removing the instrument from the mounting pole, remove the rain funnel and dump
the liquid contents that could be in the EC basin (
Figure 35
). If the liquid contents are not
emptied, the contents of the basin (dirt, bird droppings) will make a mess as the instrument
is transported.
5.2 CALIBRATION
•
Solar Radiation: ATMOS 41W pyranometers are calibrated through side-by-side comparison
to the mean of four Apogee model SP-110 transfer standard pyranometers (shortwave
radiation reference) under high-intensity discharge metal halide lamps. The transfer
standard pyranometers are calibrated through side-by-side comparison to the mean of
at least two ISO-classified reference pyranometers under sunlight (clear sky conditions)
in Logan, Utah. Each of four ISO-classified reference pyranometers are recalibrated on an
alternating yearly schedule (two instruments each year) at the National Renewable Energy
Laboratory (NREL) in Golden, Colorado. NREL reference standards are calibrated to the
World Radiometric Reference (WRR) in Davos, Switzerland.
• METER recommends using the model from the
(clearskycalculator.
com), developed by Apogee Instruments and available on
or in the
respective app store for a mobile device, to determine uncertainty of the pyranometer on
the ATMOS 41W. Should the uncertainty be higher than 5% (or other preferred number) the
unit should be replaced with a new funnel/pyranometer. Contact
