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Table of Contents
Doppler wind lidar
HALO Photonics Doppler wind lidar at JOYCE
Principle
The backscattered light from an emitted laserbeam is used to measure wind speed. Analysis of doppler shift gives wind speed along the beam. Combination of several beams allows an estimate of the three components of the wind vector. Amount of received backscattered light allows calculation of backscatter coefficient.
Measurement modes
- Vertically pointing observations with integration times of 15 seconds
JOYCE-CF Standard Operation Procedures
- Standard measurement modes are
- Vertical resolution 15 m, maximum range 15 km (CHM15k)
- Vertical resolution 30 m, maximum range 7.5 km (CT25K)
Data availability
Most of the following data products are provided via the SAMD database. If you would like to have additional data or recent data that have not been uploaded to SAMD yet, please fill the data request sheet and send it to info@joyce.cloud
| Dataset | Temporal resolution | File size | Filename | Retrieval / Remarks |
|---|---|---|---|---|
| Uncalibrated attenuated backscatter (background corrected) | 15 seconds | 1 file per day (30 MB) | sups_joy_ceilo00_l1_beta_v00_YYYYMMDDHHMMSS.nc | from CHM15k, available on SAMD |
| Mixing layer height | 15 minutes | 1 file per day (0.02 MB) | sups_joy_ceilo00_l2_zmlaa_v01_YYYYMMDDHHMMSS.nc | from CHM15k, available on SAMD |
| Backscatter, cloud base height | 15 seconds | 1 file per day (25 MB) | YYYYMMDD_JOYCE_CHM120109_000.nc | from CHM15k |
| Backscatter, cloud base height | 15 seconds | 1 file per day (6 MB) | YYMMDD_ct25k_jue_l0b.nc | from CT25K |
Composite products using data from Ceilometer
- Cloudnet target classification uses cloud base height observations from the CT25K-Ceilometer. Combined with cloud radar and microwave radiometer observation, clouds are characterized by their geometrical extent as well as their microphysical properties. Data are available via ACTRIS cloudnet website
Link to current observations
Current observations at quicklook archive
Measurement examples
Time series of brightness temperatures (left) and Integrated Water Vapor / Liquid Water Path (right)
Technical specifications
| Parameter | Specification | Remark |
|---|---|---|
| Wavelength / nm | 1500nm | |
| Pulse energy / $\mu$J | ~100 | see ARM Doppler lidar handbook |
| Pulse width / ns (m) | 150 (22.5) | see ARM handbook |
| Repetition Rates / s | 1/15000 | i.e. 15000 laser pulses per second (=Pulse repetition frequency PRF) |
| 1.67 | avg.beam i.e. N_avg pulses averaged and processed ⇒ dead time=0.67s | |
| 300 | Doppler Beam swing (DBS) with 3 beams ([azi,ele] = [0,90],[0,75],[90,75]) | |
| 900 | Velocity azimuth display (VAD) with 36 beams ([azi,ele] = [i*10,75]) | |
| 3600 | vertical slice (RHI) with 18 beams ([azi,ele] = [109,i*10]) | |
| N_avg | 15000 | number of pulses to be averaged in one 'beam' |
| resolution / m | 30 | range resolution (adjustable from 15m onward) |
| Field-of-View / deg | 360 x 90 | free alingment of the beam |
| maximum range / m | 9000 | adjustable, but restriced to sufficent backscatter (aerosol, cloud droplets or ice crystals) |
| velocity resolution / ms-1 | 0.0382 | adjustable |
| velocity precsision / ms-1 | < 0.20 | for SNR > -17dB |
| max velocity / ms-1 | 19.2 | = Nyquist Velocity (adjustable) |
| Aperture / mm (area /m2) | 75 (4.417e-3) | see ARM handbook |
| Size / cm³ | 80 x 53 x 40 | |
| Average Power consumption / W | 140/250 [600] | (wo/w Heating/cooling) [The power supply shall provide 600W] |
| Weight / kg | 110 | with transport case |
| Manufacturer | Halo Photonics | |
| Year | 2011 | |
| Instrument | streamline Instrument #17, XR version in 2010, 15kHz PRF, 10km max range |