The SGR series comprises 2 models, SGR3 and SGR4. The mechanical construction of the SGR3 differs from the SGR4 in that it
has a flat silicon window and smaller housing dimensions. Both have non replaceable desiccant. The SGR series is designed for
measuring the downward radiation (W/m²) on a plane surface from the atmosphere above.
SGR4 pyrgeometer includes an integrated bubble level, internal desiccant, white snap-on sun shield, and an optional shielded
signal output cable with connector.
SGR4 can be used in conjunction with the Kipp & Zonen CVF4 ventilation unit for enhanced measurement performance and
overall reduced instrument maintenance.
For reducing the window heating offset error, the direct solar radiation can be shielded statically from the SGR3 pyrgeometer by
the Kipp & Zonen shadow ring CM121, and fully automatically by the SOLYS2 sun tracker with shading system. This can also be
done for the SGR4 but is not really necessary because of the minimal window heating effect.
A net pyrgeometer measures both the downward atmospheric long-wave radiation and the upward long-wave radiation from the
surface below. It can be configured from two SGR4 series pyrgeometers and a suitable mounting plate. In the case of the SGR3,
two instruments can be simply mounted back-to-back and an optional mounting rod fitted.
8.1 SGR4
SGR4 has been designed for scientific measurements outdoors of downward atmospheric long-wave radiation with extremely
high reliability and accuracy.
SGR4 provides an output voltage that is proportional to the downward atmospheric long-wave radiation. SGR4 has an integrated
temperature sensor to measure the housing temperature.
SGR4 uses a specially designed silicon meniscus window. Although the window is not hemispherical, SGR4 has a 180° field of
view with good cosine response. A hard-carbon, diamond-like, coating protects the outer surface of the window and smoothes
the spectral response. On the inside, a solar blind interference filter blocks all short-wave solar radiation.
The solar radiation absorbed by the window is conducted away into the housing very effectively, by a unique construction. Even
in full sunlight the window heating offset is very low compared to that of other pyrgeometers on the market. This allows accurate
daytime measurements without the need for a tracking shading disk. It also eliminates the need for window heating compensation
by using the correction formula.
The special features of the SGR4 are:
- Sensitive to infrared radiation in a wavelength from 4.5 to 42 µm.
- Extremely low window heating offset
- 180° field of view with good cosine response
- Diamond-like coating for optimal protection against environmental influences
- Individual measured and corrected temperature dependency of sensitivity
- Direct output of Longwave downward radiation
- Via Modbus® also Net-radiation and Temperature available
8. SGR models
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