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Table of Contents
W-Band Cloud radar (JOYRAD-94)
Cloud radar JOYRAD-35 installed at Jülich
Principle
The W-Band cloud radar 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.
Measurement modes
- Vertically pointing observations with integration times up to 1 seconds.
- Full azimuth/elevation scanning capability for horizontal variability of clouds as well as 3D wind vectors in clouds
JOYCE-CF Standard Operation Procedures
- Standard measurement mode is vertically pointing, 2 second integration time
- Every 30 minutes one azimuth scan at 83° elevation angle with 6° azimuth resolution (duration ~2 minutes) for horizontal wind within clouds and the boundary layer (if sufficient insects are present)
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 MiRAC-A observations at JOYCE (radar moments / LWP)
JOYRAD-94 History
| Period | Place | Project |
|---|---|---|
| 14/06/2019 - today | AWIPEV at Ny-Ålesund, Norway | (AC)3 |
| 23/03/2018 - 06/03/2019 | Iquique, Chile | CRC1211 |
| 10/06/2016 - 26/07/2017 | AWIPEV at Ny-Ålesund, Norway | (AC)3 |
| 16/10/2015 - 23/03/2016 | Research Center Jülich, Germany | JOYCE |
MiRAC-A History
| Period | Device | Place | Project |
|---|---|---|---|
| 03/2020 - 04/2020 | MiRAC-A | Polar 5, Svalbard | |
| 31/05/2019 - 08/01/2020 | MiRAC-A | Research Center Jülich, Germany | JOYCE |
| 03/2019 - 04/2019 | MiRAC-A & -P | Polar 5, AFLUX campaign, Svalbard | (AC)3 |
| 28/07/2017 - 08/10/2018 | MiRAC-A & -P | AWIPEV Ny-Ålesund, Svalbard | (AC)3 |
| 05/2017 - 07/2017 | MiRAC-A & -P | Polar 5, ACLOUD campaign, Svalbard | (AC)3 |
Technical Specifications
| Parameter | Specification | Remark |
|---|---|---|
| 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 | |
| Polarisation | V | |
| 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 | |
| Manufacturer | RPG |