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APPENDIX I CLASSIFICATION ACCORDING TO WMO GUIDE 1996
Characteristics
ISO 9060 classification
Response time (95 percent response)
Zero offset:
2
(a) Response to 200 W/m
net thermal radiation
(ventilated)
(b) Response 5 K/h change
in ambient temperature
Resolution (smallest detectable
change)
Stability (change per year, percentage
of full scale)
Directional response of beam radiation
(The range of errors caused by
assuming that the normal incidence
responsivity is valid for all directions
when measuring, from any direction, a
beam radiation whose normal
2
incidence irradiance is 1000 W/m
Temperature response (percentage of
maximum due to any change of
ambient temperature within an interval
of 50 K)
Non-linearity (percentage deviation
2
from the responsivity at 500 W/m
to any change of irradiance within the
2
range 100 to 1000 W/m
)
Spectral sensitivity (percentage of
deviation of the product of spectral
absorptance and spectral
transmittance from the corresponding
mean within the range of 0.3 to 3 µm)
Tilt response (percentage deviation
from the responsivity at 0° tilt,
horizontal, due to change in tilt from 0°
2
to 90° at 1000 W/m
irradiance)
Achievable uncertainty, 95 percent
confidence level
Hourly totals
Daily totals
High
CM 11
quality
Secondary
standard
12 s
< 15 s
2
<± 7 W/m
<± 7 W/m
(with CV 2)
2
<± 2 W/m
<± 2 W/m
± 1 W/m
2
<± 1 W/m
< 0.5
< 0.8
2
<± 10 W/m
<± 10 W/m
)
< 1
< 2
0
0
-10
C..+40
C
due
< 0.5
< 0.5
< 2
< 2
< 0.2
< 0.5
3 %
3%
3 %
2%
APPENDIX I
Good
Moderat
quality
e quality
Second
First class
class
< 30 s
< 60 s
2
2
2
<± 15 W/m
<± 30 W/m
2
2
2
<± 4 W/m
<± 8 W/m
± 5 W/m
± 10 W/m
2
2
2
< 1.5
< 3.0
2
2
2
<± 20 W/m
<± 30 W/m
< 4
< 8
< 1
< 3
< 5
< 10
< 2
< 5
8%
20%
5%
10%
49
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