SR05-D1A3-PV manual v1801 64/83
Hukseflux main recommendations for field intercomparisons are:
1) to take normal incidence as a reference and not the entire day.
2) to take a reference of the same brand and type as the field pyranometer or a
pyranometer of a higher class, and
3) to connect both to the same electronics, so that electronics errors (also offsets) are
eliminated.
4) to mount all instruments on the same platform, so that they have the same body
temperature.
5) assuming that the electronics are independently calibrated, to analyse radiation values
at normal incidence radiation (possibly tilting the radiometers to approximately normal
incidence), if this is not possible to compare 1 hour totals around solar noon for
horizontally mounted instruments.
6) for second class radiometers, to correct deviations of more than ± 10 %. Lower
deviations should be interpreted as acceptable and should not lead to a revised
sensitivity.
7) for first class pyranometers, to correct deviations of more than ± 5 %. Lower
deviations should be interpreted as acceptable and should not lead to a revised
sensitivity.
8) for secondary standard instruments, to correct deviations of more than ± 3 %. Lower
deviations should be interpreted as acceptable and should not lead to a revised
sensitivity.
8.4 Data quality assurance
Quality assurance can be done by:
• analysing trends in solar irradiance signal
• plotting the measured irradiance against mathematically generated expected values
• comparing irradiance measurements between sites
• analysis of night time signals
The main idea is that one should look out for any unrealistic values. There are programs
on the market that can semi-automatically perform data screening. See for more
information on such a program: www.dqms.com.
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