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

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).