The HATPRO provides vertical profiles of temperature and humidity, as well as liquid water path and integrated water vapour.
The profiles are obtained from measurements of atmospheric radiation in the range of 22.24 – 31.4 GHz and 51.0 – 58.0 GHz. The radiometer comprises 7 channels in the water vapour line and 7 channels in the oxygen line at the following frequencies:

fc [GHz] (water vapour): 22.24, 23.04, 23.84, 25.44, 26.24, 27.84, 31.40
fc [GHz] (oxygen): 51.26, 52.28, 53.86, 54.94, 56.66, 57.30, 58.0           
A coupled infrared radiometer allows for cloud base height determination and ice cloud detection.