CNR4 Net Radiometer
19
TABLE 8-1. Resistance values versus CNR4’s thermistor 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
135200
127900
121100
114600
108600
102900
97490
92430
87660
83160
78910
74910
71130
67570
64200
61020
58010
55170
52480
49940
47540
45270
43110
41070
39140
37310
35570
33930
32370
30890
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
29490
28150
26890
25690
24550
23460
22430
21450
20520
19630
18790
17980
17220
16490
15790
15130
14500
13900
13330
12790
12260
11770
11290
10840
10410
10000
9605
9227
8867
8523
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
8194
7880
7579
7291
7016
6752
6500
6258
6026
5805
5592
5389
5193
5006
4827
4655
4489
4331
4179
4033
3893
3758
3629
3504
3385
3270
3160
3054
2952
2854
Relatively small errors occur when the CNR4 is not in thermal equilibrium.
This happens for example when the heater is on, or when the sun is shining.
When the heater and ventilator are on, the largest expected deviation between
the real sensor temperature and the thermistor reading is 1 degree. This results
in a worst case error for the pyrgeometer of 5 W/m
2
. When the sun is shining,
the largest expected deviation between the real sensor temperature and the
thermistor reading is again 1 degree. This results in a worst case error for the
pyrgeometer of 5 W/m
2
.
The thermistor will not give a good indication of ambient air temperature; at
1000 W/m
2
solar radiation, and no wind, the instrument temperature will rise
approximately 5 degrees above the ambient temperature.
The offsets of both the pyranometers and the pyrgeometers might be larger
than 5 W/m
2
if large temperature gradients are forced on the instrument (larger
than 5 K/hr); for example, when rain hits the instrument. This occurrence can
be detected using the thermistor readout, and can be used for data filtering.
Содержание CNR4
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Страница 52: ...Appendix B Example Programs B 14 ...
Страница 68: ...Appendix D CNF4 Heater Ventilator D 12 ...
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