The Atmospheric Propagation Profiler (ATPROP) has been developed for European Space Agency ESA. In order to quantify atmospheric perturbations on satellite signals this new ground based ultra stable microwave radiometer is developed. In addition to several K- and V-Band channels two further Ku - and W – band channels are implemented. This frequency combination provides sensitivity towards atmospheric water vapour and oxygen, as well as to rain and cloud droplets. To perform highly stable measurements, the radiometer is equipped with a continuous calibration method using a Dicke Switch and a noise diode. This yields to radiometer stability for integration times up to 2000 seconds.
The radiometer provides 7 channels on the water vapour- (K-Band) and 7 channels on the oxygen line (V-Band) for detecting humidity and temperature profiles (similar to the Humidity and Temperature Profiler HATPRO). Two additional channels have been added within Ku-band (near 15 GHz) and W-band (near 90 GHz). The system noise temperature of K-Band and Ku-Band channels are < 500 K, those of V and W-Band < 800K. The 90 GHz channel enhances the detection of cloud liquid water and (compared to HATPRO) improves the detection of clouds with lower liquid water path. The 15 GHz channel is favourable for detecting the onset of precipitation and quantity of rainfall for most conditions except the heaviest rain events. The calibration of ATPROP takes place continuously by a combination of a Dicke switch and a noise diode. It allows performing measurements without interruption by calibration. Elevation and azimuth scans can be combined to full hemispheric scan pattern. This functionality provides information on the distribution and the inhomogenities of water vapour and liquid water in time and space. Furthermore, prescribed scan pattern are able to track every specified satellite position.
|04/2008 - today||CESAR, Cabauw, Netherlands||ESA|