TRIPEx-pol level-2 data

This dataset was collected during the TRIple-frequency and Polarimetric radar Experiment for improving process observation of winter precipitation (TRIPEx-pol) campaign. During the campaign, three zenith pointing radars were operated at he research core facility Jülich ObservatorY for Cloud Evolution (JOYCE-CF, 50°54′31′′\,N, 6°24′49′′\,E; 111\,m above mean sea level) close to Cologne, Germany. The radars were measuring at X,Ka and W-band frequencies. For a detailed information on the campaign and the radars see von Terzi et al 2021. The dataset here is the LV2 data. That means that the original Doppler Spectra data was regridded to a common time height grid with 4s temporal and 36m spatial resolution. The Doppler spectra were also fitlered (see von Terzi et al 2021 level-0 processing). The moments were calculated directly from the LV0 dataset. The LV2 processing follows Dias-Neto et al. 2019 (https://doi.org/10.5194/essd-11-845-2019 ).  In the LV2 processing step, the radar specific offsets were calculated using a forward simulation of rain drop size distribution from a PARSIVEL instrument which is operated at JOYCE-CF. The calibration offsets are stored in the variable rain_offset_{band} (band stands for the radar band, so X,Ka or W). Then gaseous attenuation due to nitrogen, oxygen and water vapour were calculated from temperature, pressure and humidity profiles using the CloudNet product (more detail in von Terzi et al. 2021 lvel-2 processing). The attenuation due to gas is stored in the variable pia_{band}. Furthermore, the attenuation due to liquid or ice hydrometeors with the DWR-calibration described in Dias-Neto et al. 2019. In the DWR-calibration, the X and W-band radars are calibrated with respect to the Ka-band radar in the highest part of the cloud present. In the upper parts of ice clouds, the ice particles present can be assumed to be small enough to be Rayleigh scatterers and their reflectivity should not depend on the radar frequency. The relative radar offset is calculated for each time by looking at the reflectivity differences within a moving time window of 10 minutes. The attenuation due to liquid/ice hydrometeors is stored in the offset_{band} variable. The rain_offset_{band}, pia_{band} and offset_{band} have already been added to the radar reflectivity in the files, to return to the not-offset corrected dataset, simply subtract the named offsets. The variables quality_flag_offset_{band} contains flags indicating how trustworthy the offset correction is.