Open Access to Five Years of Calibrated Measurements of the Polarimetric X-band Weather Radar in Bonn (BoXPol)

Compared to conventional weather radars, dual-polarimetric radar systems can provide more precise information about precipitation amounts, types, shapes, concentration, drop size distributions, and precipitation processes. The wealth of information is exploited to improve our understanding on precipitation generating processes, to evaluate and improve numerical weather prediction models and provide more accurate (short-term) forecasts and severe weather warnings. As support for this research we provide and describe a five years (2014 - 2019) open-access dataset measured with the dual-pol Doppler X-band (9.3 GHz) weather radar in Bonn (BoXPol), western Germany. The BoXPol data set is archived by the German Climate Computing Centre (DKRZ) as daily NetCDF files consisting of all important polarimetric variables for each of the ten plan position indicator scans. Furthermore, supporting notebooks for processing and visualization of the polarimetric data are provided with the data set. The radar scanning strategy, the technical radar information and the best practice for radar data processing, like e.g. differential phase processing, derivation of specific differential phase, partial beam blockage detection and attenuation correction, are described as well. We compare the ground-based radar reflectivity measurements with the satellite observations of the Dual- frequency Precipitation Radar, operating on the core satellite of the Global Precipitation Mission, to provide absolute calibration offsets with the data set.  Stable calibration periods are identified with the Relative Calibration Adjustment technique using reflectivity statistics generated from local stable clutter.  Absolute calibration for the differential reflectivity measurements is determined using the vertically pointing scan (birdbath scan) and provided as well.