====== G-band Radar for Water vapor profiling and Arctic Clouds GRaWAC ======


===== Principle =====

GRaWAC is an active Frequency Modulated Continuous Wave (FMCW) cloud radar with dual frequencies at 167.3 and 174.7 GHz with Doppler capabilities. GRaWAC can be operated on an aircraft (nadir looking) or from the ground (zenith observations).\\

At both frequencies, the cloud radar transmits saw tooth frequency chirps. The combination of the two frequencies close to the 183.3 water vapor absorption line enables the retrieval of water vapor profiles with the Differential Absorption Radar technique (DAR) in cloudy and precipitating conditions. It has a vertical resolution of 30 m and a sensitivity of -43 dBZ at 1 km, 1 s. \\

===== Instrument =====
{{:instruments:grawac:grawac.png?400|GRaWAC}}

GRaWAC during test measurements at ([[http://www.radiometer-physics.de/|RPG]]).\\


===== Specifications GRaWAC (G-band GHz FMCW cloud radar)=====
^ Parameter  ^ Specification  ^ Remark  ^
| Frequency | 176.3 ± 0.1 GHz   &   174.7 ± 0.1 GHz |  |
| Wavelength | 1.8 mm & 1.7 mm | |
| Transmitter Power | 70 mW & 90 mW | |
| Antenna gain | 54.6 dB |  |
| Receiver Noise | 5.5 dB |  |
| Receiver Intermediate Frequency | 4 MHz | |
| Dynamic Range | 58 dB |  |
| Antenna Diameter | 0.5 m | |
| Beam Width | 0.36° |  |
| Power consumption | 700 W | |
| Weight | 116 kg | |
| Dimensions | 115 cm x 90 cm x 90 cm | |
| Chirp Variations | 4 typical | 10 possible, re-programmable |
| 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) |  |
| Manufacturer | [[http://www.radiometer-physics.de/|RPG]] |