Campbell NR01, Инструкция по эксплуатации

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NR01 Four-Component Net Radiation Sensor
14
The equation for the SW
albedo
is as follows:
SW
albedo
= SW
in
/ SW
out
7-8
The following equations assume the temperature is in Kelvin.
Add 273.15 to equations 7-9 and 7-10 for temperature in degree
Celsius.
T
surface
= (LW
out
/5.67.10 -8 ) 1/4 7-9
T
sky
= (LW
in
/5.67.10 -8 ) 1/4 7-10
7.1.1 Pyranometers
A pyranometer measures the solar or SW radiation flux from a field of view of
180 degrees. The atmospheric SW radiation spectrum extends roughly from
300 to 2800 nm. The pyranometer should cover that spectrum with a spectral
sensitivity that is as flat as possible.
For a flux measurement, it is required by definition that the response to beam
radiation varies with the cosine of the angle of incidence. For example, full
response occurs when the solar radiation hits the sensor perpendicularly
(normal to the surface, sun at zenith, 0 degrees angle of incidence); zero
response occurs when the sun is at the horizon (90 degrees angle of incidence,
90 degrees zenith angle), and half a response occurs at 60 degrees angle of
incidence. It follows from the definition that a pyranometer should have a so-
called directional response or cosine response that is close to the ideal cosine
characteristic.
In order to attain the proper directional and spectral characteristics, a
pyranometer’s main components are:
1. Thermopile sensor with a black coating – absorbs all solar radiation,
provides a flat spectrum covering the 300 to 50000-nanometer range, and
has a near-perfect cosine response.
2. Glass dome – limits the spectral response from 300 to 2800 nanometers
(cutting off the part above 2800 nm) while preserving the 180 degrees field
of view (FIGURE 7-1 ). Another function of the dome is that it shields the
thermopile sensor from convection.
NOTE