Introducing the path-integrated attenuation as an additional filter in the quality index of spaceborne and ground-based radar calibration bias estimates

This study analyses polarimetric weather radar data to explore their potential for comprehensive and reliable precipitation and thus, drought monitoring in Cyprus. For this purpose, we compare reflectivity measurements from the two ground-based X-band dual-polarization radars of the Department of Meteorology of the Republic of Cyprus with measurements obtained from the Dual-Frequency Precipitation Radar (DPR) onboard NASA’s Global Precipitation Measurement (GPM) mission. The comparison considers six years (2017–2023) of observations. It is implemented using the volume-matching method proposed by Schwaller and Morris (2011), as extended by Crisologo et al (2018) to take into account the beam blockage fraction as the basis of a quality index. To further enhance the consistency and precision of the calibration bias, we introduce path-integrated attenuation as an additional filter in the quality index. The path-integrated attenuation of the ground radars is estimated using a forward gate-by-gate attenuation correction method based on an iterative approach with scalable constraints. The level of path-integrated attenuation of the GPM Dual-Frequency Precipitation Radar is evaluated based on the GPM 2AKu variable piaFinal. Acknowledgements The 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.