Accurate Airborne Surface Temperature Measurements with Chopper-stabilized Radiometers

Abstract

The accuracy of chopper-stabilized radiometers for the meteorological measurement of surface temperatures was investigated during a series of airborne trails, including tests at high altitude using a pressurized aircraft. The significant finding was that these radiometers need to be frequently calibrated during flight to ensure accurate readings of the target's infrared output. Laboratory calibration, prior to flight, is a requirement but alone not sufficient. To adapt the author's radiometer to fit into the fuselage of the pressurized aircraft, a plane mirror was installed in front of the radiometer. Theoretical calculations, supported by test results, indicated that the mirror did not affect the device's accuracy. On the contrary, the mirror can be used as a means to compensate for the influence of ambient temperature fluctuations in the immediate vicinity of the radiometer.