Hukseflux SR05 series - Page 60

SR05-D1A3-PV manual v1801 60/83
Table 7.4.1.1 Preliminary estimates of achievable uncertainties of measurements with
Hukseflux pyranometers. The estimates are based on typical pyranometer properties and
calibration uncertainty, for sunny, clear sky days and well maintained stations, without
uncertainty loss due to lack of maintenance and due to instrument fouling. The table
specifies expanded uncertainties with a coverage factor of 2 and confidence level of
95 %. Estimates are based on 1 s sampling. IMPORTANT NOTE: there is no international
consensus on uncertainty evaluation of pyranometer measurements, so this table should
not be used as a formal reference.
Pyranometer
class
(ISO 9060)
season latitude uncertainty
minute totals
at solar noon
uncertainty
hourly totals
at solar noon
uncertainty
daily totals
secondary
standard
summer
mid-latitude
2.7 %
2.0 %
1.9 %
equator
2.6 %
1.9 %
1.7 %
pole
7.9 %
5.6 %
4.5 %
winter
mid-latitude
3.4 %
2.5 %
2.7 %
first class
summer
mid-latitude
4.7 %
3.3 %
3.4 %
equator
4.4 %
3.1 %
2.9 %
pole
16.1%
11.4 %
9.2 %
winter
mid-latitude
6.5 %
4.5 %
5.2 %
second class
summer
mid-latitude
8.4 %
5.9 %
6.2 %
(SR05 series)
equator
7.8 %
5.5 %
5.3 %
pole
29.5 %
21.6 %
18.0 %
winter
mid-latitude
11.4 %
8.1 %
9.9 %
7.4.2 Calibration uncertainty
New calibration procedures were developed in close cooperation with PMOD World
Radiation Center in Davos, Switzerland. The latest calibration method results in an
uncertainty of the sensitivity of less than 1.8 %, compared to typical uncertainties of
higher than 3.5 % for this pyranometer class. See the appendix for detailed information
on calibration hierarchy.