GPM DPR-Based Calibration of two Ground-based Weather Radars

In the past decades, ground-based weather radars gained popularity for enhancing the understanding of precipitation systems, the accuracy of the Quantitative Precipitation Estimation (QPE) and for serving as input in numerical weather models. Nevertheless, they are prone to errors from various sources, including significant calibration errors. Previous research showed that the Ku-band precipitation radar aboard the Global Precipitation Measurement Mission Dual-Precipitation Radar (GPM DPR) is effective for calibrating ground-based radars. Several studies proposed the alignment of ground-based radar reflectivities with those from the GPM DPR to achieve their absolute calibration. This study performs the absolute calibration of the Rizoelia (LCA) and Nata (PFO) radars in Cyprus for approximately six years of observations (October 2017 to May 2023), assessing and comparing volume-matching thresholds and data filtering techniques. The results indicate that excluding reflectivities within the melting layer and adding a 250 m buffer consistently improved calibration for both radars. The selected calibration schemes were combined, and the resulting offsets were compared against stable radar parameters to identify stable calibration periods. Future work will include disdrometer data and expand the analysis to quantitative precipitation estimation.AcknowledgementsThe authors acknowledge the ‘EXCELSIOR’: ERATOSTHENES: EΧcellence Research Centre for Earth Surveillance and Space-Based Monitoring of the Environment H2020 Widespread Teaming project (www.excelsior2020.eu). The ‘EXCELSIOR’ project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No 857510, from the Government of the Republic of Cyprus through the Directorate General for the European Programmes, Coordination and Development and the Cyprus University of Technology.The authors also acknowledge the Department of Meteorology of the Republic of Cyprus for providing the X-band radar data.