Mentor: R. Gierens
The cloud radar JOYRAD-94 is a Frequency Modulated Continuous Wave (FMCW) Radar that transmits saw tooth frequency chirps at 94 GHz. In this way, vertical profiles of reflectivity, Doppler velocity, Doppler spectral width are detected from 150 m to 10 km above ground. Given these measurements, information on the macrophysical (cloud boundaries, type of cloud particles) and microphysical (e.g., liquid and ice water content) properties of the detected cloud can be derived. The radar is operated in a vertically pointing mode. Additionally, the system is equipped with a passive radiometric channel at 89 GHz that is sensible to cloud liquid water. Passive and active receivers are fed by the same antenna, i.e. a perfect beam overlap is accomplished.
JOYRAD-94 (RPG) at Forschungszentrum Jülich on the roof of the IEK-8 (Institut für Energie- und Klimaforschung: Troposphäre).
The figure shows the brightness temperature from the passive 89 GHz channel of JOYRAD-94 as well as radar reflectivity factor, Doppler velocity and Doppler spectral width of the JOYRAD-94 measurements.
Gray areas indicate no data.
|Frequency||94 GHz ± 100 MHz||corresponds to wavelength of 3.19 mm; adjustable by software between 92.3 and 95.7 GHz|
|IF Range||350 kHz to 3 MHz|
|Transmitter Power||~ 2 W||solid state amplifier|
|Antenna gain||51.6 dB|
|Beam Width||0.48° FWHM|
|System Noise Figure||3 dB|
|Dynamic Range||-54 dBZe to +20 DBZe at 1km height, -45 dBZe to +20 dBZe at 3 km height, -36 dBZe to +20 dBZe at 10 km height|
|Ranging||50 m to 18 km|
|Calibration||Transmitter power monitoring, Receiver Dicke switch (for radar and DD channels), Hot/Cold absolute receiver calibration||Accuracy 0.4 dB|
|A/D Sampling Rate||8.2 MHz|
|Profile Sampling Rate||0.2 s to 30 s|
|Vertical Resolution||1 m to 100 m||(user selectable)|
|Doppler Resolution||± 1.5 cm/s|
|Doppler Range||± 18 m/s max.|
|Chirp Variations||4 typical||10 possible, re-programmable|
|Passive Channels||89 GHz|
|Data Products||Reflectivity, Doppler-velocity, Spectral Width, Higher Moments, Doppler Spectra, LWC profiles|
|Data Formats||proprietary binary, netCDF (conformity with CF convention), ASCII (only moment profiles)|
|Rain / Snow Mitigation System||Super blower for rec. / transm. radome (2000 m³/h each)||Optional heater modules (2 kW to 4 kW)|
|Weight||Radar main body: 100 kg, Table: 130 kg, Air conductors: 25 kg|
|Power Consumption||220 V AC, 50-60 Hz, Radar: 400 W, Blowers: 1000 W|