Air temperature installation

For air temperature measurements, locate probes over an open, level area at least 9 m (EPA; Attributions and references) 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:

When exposed to sunlight, the 108 should be housed in a six-plate solar radiation shield. Six-plate shields offered by Campbell Scientific are models 41303-5A, 41303-5B, or RAD06.

The white color of these shields reflects solar radiation, and the louvered construction allows air to pass freely through, thereby keeping the probe at or near ambient temperature. The RAD06 uses a double-louvered design that offers improved sensor protection from insect intrusion and driving rain and snow. In addition, the RAD06 shield has lower self-heating in bright sunlight combined with higher temperatures (> 24 °C (75 °F)) and low wind speeds (< 2 m/s (4.5 mph)), giving a better measurement.

The 41303-5A and RAD06 attach to a crossarm, mast, or user-supplied pipe with a 2.5 to 5.3 cm (1.0 to 2.1 in) outer diameter. The 41303-5B attaches to a CM500-series pole or a user-supplied pole with a 5.1 cm (2.4 in) outer diameter.

Tools required for installing a radiation shield to a tripod or tower include:

  • 1/2-inch open end wrench

  • UV resistant cable ties

  • adjustable wrench with a minimum 1-1/2 inch jaw size

Installing a 108 and 41303-5A Radiation Shield on a CM200-Series Crossarm

    

108 and 41303-5A Radiation Shield on a tripod mast (left).
108 and RAD06 Radiation Shield on a CM200-Series Crossarm (right).

The 108 is held in the 41303-5A radiation shield by a mounting clamp at the bottom (Installing a 108 and 41303-5A Radiation Shield on a CM200-Series Crossarm and 108 and 41303-5A Radiation Shield on a tripod mast (left).108 and RAD06 Radiation Shield on a CM200-Series Crossarm (right). left). Loosen the mounting clamp screws, and insert the probe through the clamp. Tighten the screws to secure the sensor, and route the sensor cable to the instrument enclosure.

The 108 is held in the RAD06 radiation shield by inserting the sensor through the sensor gland at the bottom of the shield (108 and 41303-5A Radiation Shield on a tripod mast (left).108 and RAD06 Radiation Shield on a CM200-Series Crossarm (right). right). Loosen the nut on the gland, and insert the probe into the shield. Tighten the nut on the sensor gland using an adjustable wrench until the sensor is securely held in place. Route the sensor cable to the instrument enclosure.

Secure the cable to the tripod or tower using cable ties.