Specifications

CNR4 Net Radiometer
TABLE 5-2. Resistance values versus CNR4's Pt-100 temperature in °C.
Temperature
[°C]
Resistance
[Ω]
Temperature
[°C]
Resistance
[Ω]
Temperature
[°C]
Resistance
[Ω]
-30
-29
-28
-27
-26
-25
-24
-23
-22
-21
-20
-19
-18
-17
-16
-15
-14
-13
-12
-11
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
88.22
88.62
89.01
89.40
89.80
90.19
90.59
90.98
91.37
91.77
92.16
92.55
92.95
93.34
93.73
94.12
94.52
94.91
95.30
95.69
96.09
96.48
96.87
97.26
97.65
98.04
98.44
98.83
99.22
99.61
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
100.00
100.39
100.78
101.17
101.56
101.95
102.34
102.73
103.12
103.51
103.90
104.29
104.68
105.07
105.46
105.85
106.24
106.63
107.02
107.40
107.79
108.18
108.57
108.96
109.35
109.73
110.12
110.51
110.90
111.28
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
111.67
112.06
112.45
112.83
113.22
113.61
113.99
114.38
114.77
115.15
115.54
115.93
116.31
116.70
117.08
117.47
117.85
118.24
118.62
119.01
119.40
119.78
120.16
120.55
120.93
121.32
121.70
122.09
122.47
122.86
5.4 Calculation of Albedo
Albedo is the ratio of reflected short-wave radiation to incoming short-wave
radiation. This unitless value ranges between 0 and 1. Typical values are 0.9
for snow, and 0.3 for grassland. To determine the albedo, the measured values
of the two pyranometers can be used. The pyrgeometers are not involved, as
they do not measure short-wave solar radiation. Do not use the measured
values when the solar elevation is lower than 10 degrees above the horizon.
Errors in the measurements at these elevations are likely and yield unreliable
results. This is due to deviations in the directional response of the
pyranometers.
Albedo = (E lower Pyranometer) / (E upper Pyranometer) (5-3)
12