Micro Rain Radar

Micro Rain Radar installed at Jülich

Principle

The Micro Rain Radar (MRR) is a vertical pointing FM-CW (frequency modulated –continuous wave) Doppler radar operating at 24.1 GHz (K-band, 12.4 mm wavelength). The emitted radar signal (only 50 mW transmitting power) is backscattered by falling hydrometeors (rain, graupel, snow). From the Doppler spectra the radar reflectivity factor (Ze) and the terminal fall velocity distribution can be derived.

In case of rain the Doppler spectra can be used to derive vertical profiles of microphysical rain properties like drop size distribution and rain rate.

The MRR system was also studied for its potential to observe snowfall (Kneifel et al., 2011). Also, an improved MRR algorithm most suitable for snowfall observations has been developed at IGMK (Maahn and Kollias, 2012). It is freely available on Github.

Measurement modes

Vertically pointing observations with integration times from 10 to 3600 seconds.
The range resolution can be varied from 10 to 200 m which determines together with the 30 range gates the system's maximum height range of 300 to 6000 m.

JOYCE-CF Standard Operation Procedures

Temporal resolution 10 seconds
Vertical resolution 35 meters (max. range = 1085 m)

Calibrations and data quality assurance procedures

Check with co-located disdrometer to find out reflectivity offsets
Consistency check with other cloud radars

Data availability

Some of the following data products are provided via Cloudnet ACTRIS cloudnet website with a temporal resolution of 30 seconds. If you would like to have additional data with better resolution or raw Doppler spectra please fill the data request sheet and send it to info@joyce.cloud

Dataset	Temporal resolution	File size	Filename	Remarks
Radar reflectivity factor	30 seconds	1 file per day (30-50 MB)	YYYYMMDD_juelich_categorize.nc	available via Cloudnet
Doppler velocity	30 seconds	1 file per day (30-50 MB)	YYYYMMDD_juelich_categorize.nc	available via Cloudnet
Spectral width	30 seconds	1 file per day (30-50 MB)	YYYYMMDD_juelich_categorize.nc	available via Cloudnet
Linear depolarization ratio	30 seconds	1 file per day (30-50 MB)	YYYYMMDD_juelich_categorize.nc	available via Cloudnet
Profiles of horizontal wind	30 minutes	1 file per day (30-50 MB)	YYYYMMDD_joyrad35_wind_profile.nc
Radar moments	2 seconds	variable size (up to 30 MB/hour in case of thick clouds)	YYYYMMDD_HHMM.mmclx.gz	zipped NetCDF file
Doppler spectra, Radar moments	2 seconds	variable size (up to 2 GB/hour in case of thick clouds)	YYYYMMDD_HHMM.znc	NetCDF file
Doppler spectra	2 seconds	variable size (up to 1 GB/hour in case of thick clouds)	YYYYMMDD_HHMM.zspc	Binary file

Dual-wavelength ratio Ka/X-Band and Ka/W-Band Link to Quicklooks
Cloudnet target classification uses Radar moments data from JOYRAD-35. Combined with microwave radiometer and ceilometer observation, clouds are characterized by their geometrical extent as well as their microphysical properties.

Link to current observations

Data quicklooks can be found in the JOYCE quicklook archive and in the METEK archive

Measurement examples

Example time series of JOYRAD-35 observations (radar moments / horizontal wind)

Example time series of Cloudnet target classification

JOYRAD-35 History

Period	Place	Project
2017		Instrument upgrade
09/03/2012 - today	Research Center Jülich, Germany	JOYCE
08/11/2011 - 08/03/2012	Munich Airport, Germany	iPort campaign
03/2011 - 07/11/2011	Research Center Jülich, Germany	JOYCE

Cloud radar JOYRAD-35 installed at Jülich

Technical Specifications

Parameter	Specification
Frequency	24.1 GHz
Wavel	12.4 mm
Radar Type	FM-CW
Transmit Power	50 mW
Receiver	Single Polarization
Power consumption (radar)	25 W
Total power cons. incl heating	525 W
Max. range	6 km
Range Resolution	10-200 m
No. of range gates	30
Temporal resolution	10 s
Antenna diameter	0.5 m
Beam width (2-way, 6 dB)	1.5°
Manufacturer	Metek