TOPHAT is a HATPRO microwave radiometer, installed at Jülich. It was originally a G2 radiometer, and was upgraded in 2016 to G5 receivers.

HATPRO-TOPHAT installed at Jülich

HATPRO (Humidity And Temperature PROfiler) is a passive microwave radiometer manufactured by Radiometer Physics GmbH installed at the Forschungszentrum Jülich as part of JOYCE. It measures brightness temperatures at 7 channels along the slope of the water vapor absorption line at 22 GHz and at 7 channels along the slope of the oxygen absorption complex at 60 GHz with allow the retreival of integrated water vapor (IWV), cloud liquid water path (LWP) as well as tropospheric and humidity temperature profiles.

Zenith measurements alternate with RHI towards the north and PPI scans at 30 degrees elevation. Scan patterns are partially synchronized with the neighbouring cloud radar. Additionally, regular elevation scans within provide high-quality temperature profiles in the boundary layer. Attached to the side, it also includes two broadband infrared pyrometers, sensitive to water vapor, low-LWP (< 50 gm^-2) liquid clouds as well as ice clouds.

HATPRO-TOPHAT installed at Jülich