Microwave radiometry for detecting road ice

An experimental study aiming at detecting different road conditions by means of millimeter wave radiometry has been conducted in open-air laboratory using a sample of asphalt as target and two dual polarised radiometer at 10 and 37 GHz. It has been found that, when a thin (3 mm) ice crust is formed on the dry iced material, by spraying water, there is an increase of the brightness temperature higher than 15 Kelvin at 37 GHz horizontal polarisation. When, after deicing, the sample becomes wet, the brightness temperature steeply decreases by about 60 Kelvin at both frequencies and polarisations.