Campbell-scientific CNR4 Net Radiometer Manuel d'utilisateur télécharger pdf (Page 24)

CNR4 Net Radiometer

TABLE 7–2. 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

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

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

7.1.4 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 are used. 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) (7-3)

In the equation above, E is calculated according to the Equation 7-1.

1 2 ... 19 20 21 22 23 24 25 26 27 28 29 ... 63 64

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