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


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.



GRaWAC during test measurements at (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 RPG
instruments/grawac/grawac.txt · Last modified: 2024/04/19 13:13 by lbuehler