Campbell Scientific 109-L Temperature Probe - Manual (Page 16)

Model 109 Temperature Probe
7.3 Air Temperature Installation
For air temperature measurements, locate probes over an open level area at
least 9 m (EPA) in diameter. The surface should be covered by short grass or
the natural earth surface where grass does not grow. Probes should be located
at a distance of at least four times the height of any nearby obstruction, and at
least 30 m (EPA) from large paved areas. Sensors should be protected from
thermal radiation, and adequately ventilated.
Standard air temperature measurement heights:
• 1.25 to 2.0 m (WMO)
• 2.0 m (EPA)
• 2.0 m and 10.0 m for temperature difference (EPA)
When exposed to sunlight, the 109 should be housed in a 41303-5A or 41303-
5B six-plate solar radiation shield. The white color reflects solar radiation, and
the louvered construction allows air to pass freely through, thereby keeping the
probe at or near ambient temperature. The 41303-5A attaches to a crossarm,
mast, or user-supplied pipe with a 2.5 to 5.3 cm (1.0 to 2.1 inch) outer
diameter. The 41303-5B attaches to a CM500-series pole or a user-supplied
pole with a 5.1 cm (2.4 inch) outer diameter.
Tools required for installing a radiation shield to a tripod or tower include:
• 1/2 inch open end wrench
• small screw driver provided with datalogger
• small Phillips screwdriver
• UV resistant cable ties
• small pair of diagonal-cutting pliers
FIGURE 7-1. 109 and 41303-5A Radiation Shield on a Tripod Mast
41303-5A
109
Tripod Mast
or Tower Leg
8