The Ophir III radiometer estimates air temperature by measuring the infrared radiance from atmospheric carbon dioxide at 4.3 micrometers.
Output data rate is 1 sample per second.
In clear, air reported temperature is a weighted average over a path of tens of meters at low altitudes to many hundreds of meters at high altitude extending horizontally away from the aircraft. It is not stabilized so when the aircraft rolls the sensor may report higher or lower temperature than the actual ambient temperature as a result of looking up or down to different air temperatures. Liquid water is very opaque to 4.3 µm radiation so the averaging path in cumulus clouds is as short as 10 meters.
Calibration constants determined by least-squares fit to ATX, typically on a per-project basis.
