Campbell CNR4 Manual de instrucciones descargar pdf (Pagina 55)

Appendix C. CNR4 Performance and Measurements under Different Conditions

FIGURE C-3. Clear day for the downward facing pyrgeometer

It is assumed that when ambient temperature varies, the net far infrared

radiation remains roughly the same, independent of ambient temperature. The

resulting measured values of the pyrgeometers and pyranometers are shown in

columns 4 to 7 in TABLE C-1. These are indicative figures only, they depend

strongly on other circumstances; the pyrgeometer results, of course, change

with the sensor temperature. This is indicated in column 8. During the day,

the Pt-100 reading may rise due to solar heating, up to 10 degrees above

ambient temperature. During the night, the sensor temperature may be lower

than the ambient temperature due to far infrared radiative cooling. The latter

two effects do not influence the end result of the calculations of sky T and

ground T. Therefore, they are not taken into account in the table. In column 4,

one might expect to see “0 to –50” for all positions that are showing “0”; in

column 5, the “0” values may in reality be “–20 to +20”. The resulting sky

temperature is indicated in column 9. Under cloudy conditions, this sky

temperature is equal to ambient temperature. Under clear conditions, the sky

temperature is lower than the ambient temperature.

The ground temperature, in column 10, is assumed to be equal to the ambient

temperature. In practice, it may be higher during the day, due to solar heating.

Ground temperature may be lower than ambient during the night, due to far

infrared radiative cooling. The sky and the ground temperature can be

calculated from the measured values of the sensors using formulas C-1 and C-2

below.

upwelling signal (downward facing) pyrgeometer

-30

-20

-10

0:00:00

1:00:00

2:00:00

3:00:00

4:00:00

5:00:00

6:00:00

7:00:00

8:00:00

9:00:00

10:00:00

11:00:00

12:00:00

13:00:00

14:00:00

15:00:00

16:00:00

17:00:00

18:00:00

19:00:00

20:00:00

21:00:00

22:00:00

23:00:00

0:00:00

Pyrgeometer: U-emf / sensitivity [W/m²] Temp of instrument [°C]

Upwelling Signal (Downward Facing) Pyrgeometer

C-3

1 2 ... 50 51 52 53 54 55 56 57 58 59 60 ... 69 70

Comentarios a estos manuales

Sin comentarios

Campbell CNR4 Manual de instrucciones Pagina 55

Comentarios a estos manuales

Relacionado con productos y manuales para De medición, control y control Campbell CNR4