Doppler lidar measurements from the Wind and Storms Experiment (WASTEX)

The dataset contains Doppler lidar measurements for 10 days, each corresponding to an extratropical cyclone sampled during the WASTEX field campaign (see Pantillon et al. 2018).

Three data are saved in three files per day, e.g. for 23/2/2017:

• Save_KIT_DOPPLERLIDAR_RV_20170223.nc (RV = Radial Velocity → wind measurements)
• Save_KIT_DOPPLERLIDAR_SNR_20170223.nc (SNR = Signal to Noise Ratio → data quality)
• Save_KIT_DOPPLERLIDAR_BS_20170223.nc (BS = BackScatter → signal strength)

Files are in netCDF format with the following structure, e.g. for RV:

netcdf Save_KIT_DOPPLERLIDAR_RV_20170223 {
dimensions:
time = 444035 ;
ranges = 110 ;
variables:
double time(time) ;
time:standard_name = "time" ;
time:units = "seconds since 1970-01-01 00:00:00 UTC" ;
double ranges(time, ranges) ;
ranges:unit = "m" ;
ranges:long_name = "distance of range gate from lidar along the beam. value denotes the middle of the range gate." ;
double elevation(time) ;
elevation:long_name = "elevation angle of the laser beam: zenith=90, horizontal=0 and 180" ;
elevation:unit = "degree" ;
double azimuth(time) ;
azimuth:standard_name = "sensor_azimuth_angle" ;
azimuth:long_name = "azimuth angle of the laser beam: north=0, east=90, south=180, west=270" ;
azimuth:unit = "degree" ;
double radial_velocity(time, ranges) ;
radial_velocity:standard_name = "radial_velocity_of_scatterers_away_from_instrument" ;
radial_velocity:unit = "m s^-1" ;
radial_velocity:_FillValue = -999. ;
// global attributes:
:Institution = "Karlsruhe Institute of Technology, Institute of Meteorology and Climate Research" ;
:Title = "Scanning doppler lidar WindTracer" ;
}

Wind measurements are stored in variable "radial_velocity" as function of coordinates "time" and distance from lidar "ranges". At the beginning of every hour, the mean wind direction is determined (about 1500 records) with varying azimuth (“horizontal angle”) from 0° to 360° and fixed elevation (“vertical angle”) at 15° and 75°. Then the radial wind speed is measured for one hour (about 15000 records) with constant azimuth in the mean wind direction determined above and varying elevation from 0° to 15°, up and downward every 0.6°. One up- or downscan contains about 25 records contained in one up or downscan, which can be combined into one snapshot (see example in Pantillon et al. 2018). Such a “snapshot” actually contains asynchronous records (a few seconds altogether) thus it is recommended to use upscans or downscans only. Each record can be additionally filtered according to its quality, e.g. with signal-to-noise ratio SNR > -6 dB.