First Results from a Semiconductor Based 94-GHz FM-CW Doppler Radar Cloud Profiler

A new 94-GHz FM-CW Doppler radar cloud profiler is operated at the Institute for Tropospheric Research in Leipzig, Germany. This radar is for dual purpose use in a ground based or an airborne setup. The generation of transmitted power for this radar is based exclusively on semiconductor elements. Therefor, the radar front end can be directly connected to the airplane power supply in its airborne setup. The radar front end as well as the signal processing system will be described. After this short insight into the technique of this unique radar system, first results will be presented.

The presentation of first results will focus on a sensitivity estimation and a coarse calibration of the radar system. This is done by comparing radar measured backscatter spectra from stratiform rain under calm wind conditions with data from a ground based rain gauge located nearby. The radar constant, connecting the received power to the radar reflectivity factor Z of the target hydrometeors, can be adjusted so, that the radar received power matches the radar reflectivity factor Z calculated from the rain gauge measured rain rate R with an accepted Z-R relationship. Some additional results will accomplish this main focus.

In the last part, the next steps of radar enhancement will be indicated, and the resulting performance will be estimated in consideration of the presented findings. Operational plans basing on the described enhancements will be detailed. The first main goal is to operate the fully enhanced cloud profiler in its ground based set up during the 4D-CLOUDS field campaign in fall 2001 in the Netherlands. The contribution will be concluded by an outlook to future applications.