Campbell CNR1 Specifikace stáhnout pdf (Strana 11)

CNR1 Net Radiometer

Net Solar radiation = (E upper CM3) - (E lower CM3) (4.4)

In this formula E is calculated according to Equation 4.1.

Net Solar radiation will always be positive. Checking this can be used as a tool

for quality assurance of your measured data.

4.6 Calculation of the Net Infrared Radiation (Net Long-Wave)

Net Far Infrared radiation is, like Net Solar radiation, the part that contributes

to heating or cooling of the earth's surface. In practice, most of the time Net

Far Infrared radiation will be negative.

Net Far Infrared radiation = (E upper CG3) - (E lower CG3) (4.5)

In this formula E is calculated according to Equation 4.2. From this equation

the term with T cancels.

The E measured with the CG3 actually represents the irradiance of the sky (for

the upward- facing CG3) or the ground (for the downward-facing CG3).

Assuming that these two, ground and sky, behave like perfect blackbodies

(actually this is only in theory), one can calculate an effective "Sky

temperature" and an effective "Ground temperature".

Sky temperature

E upper CG3

⋅

⎡

⎣

⎢

⎤

⎦

⎥

−

567 10

(4.6)

Ground Temperature

E lower CG3

⋅

⎡

⎣

⎢

⎤

⎦

⎥

−

567 10

(4.7)

As a rule of thumb, for ambient temperatures of about 20 degrees Celsius, one

can say that one degree of temperature difference between two objects results

in a 5 Watts per square meter exchange of radiative energy (infinite objects):

1 degree of temperature difference = 5 Watts per square meter (rule of thumb)

4.7 Calculation of the Net (total) Radiation

In the 4 Separate Components Mode, Net radiation, NR, can be calculated

using the individual sensor measurement results:

NR = (E upper CM3) + (E upper CG3) -

(E lower CM3) - (E lower CG3) (4.8)

Where E is the irradiance that is calculated for the CM3 according to Equation

4.1, for the CG3 according to Equation 4.2, the terms with T cancel from this

equation.

5. Wiring

Figure 5-1 shows the CNR1 schematic with the four radiation outputs, Pt-100

temperature sensor, and the heater. The use of the heater is described in detail

in the Kipp & Zonen manual. All wiring schemes shown in this manual will

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 31 32

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