CAOS rain rate and reflectivity data set of 6 disdrometres and 2 micro rain radars at 3 different heights at 6 stations in the Attert catchment, Luxembourg from Oct 2012 - Sept 2016

DISDROMETER:We deployed six second generation OTT Particle Size and Velocity (PARSIVEL², see Löffler-Mang and Joss, 2000 - https://doi.org/10.1175/1520-0426(2000)017<0130:AODFMS>2.0.CO;2) optical disdrometers in the study area to measure drop size distributions at ground level in 1-minute resolution. Two were located at the same sites as the MRRs (Useldange and Petit-Nobressart). The others were placed such as to both capture the hydroclimatic variations in the study area and to cover it as uniformly as possible. We applied a quality control to the raw data as described by Friedrich et al. (2013 - https://doi.org/10.1175/JTECH-D-12-00254.1 and https://doi.org/10.1175/MWR-D-12-00116.1 ), converted the filtered data to drop-size concentrations per unit air volume to make them comparable to weather radar and MRR data, then converted them to reflectivity and rain rate using the 3.5th and 6th statistical moments of the drop size distributions and finally took 1-hour averages and sums thereof. MRR: From two vertical pointing K-band METEK micro rain radars (MRR) (Löffler-Mang et al. 1999 - https://doi.org/10.1175/1520-0426(1999)016<0379:OTPOAL>2.0.CO;2 and Peters et al. 2002 - Rain observations with a vertically looking Micro Rain Radar (MRR). Boreal Env. Res. 7: 353–362, 2002) measurements located at the sites Useldange and Petit-Nobressart drop size spectra were retrieved at 1500 meter and 100 meter above ground . We operated the MRR's at 100 vertical meters and 10 seconds temporal resolution, but for reasons of storage and processing efficiency did all further processing on 1-minute aggregations thereof. The raw Doppler spectra were transformed to drop size distributions via the drop size – fall velocity relation given in Atlas et al (1973 - https://doi.org/10.1029/RG011i001p00001). From the drop size distributions the rain rate and the reflectivity were calculated using the 3.5th and the 6th statistical moments of the drop size distributions. In doing so we assumed the vertical velocity of the air to be negligible.