Calibration of Two X-Band Ground Radars Against GPM DPR Ku-Band
Journal
Remote Sensing
Date Issued
May 14, 2025
Abstract
Weather radars are essential in the Quantitative Precipitation Estimates (QPE) but
are susceptible to calibration errors. Previous work demonstrated that observations from
the Ku-band Dual Polarization Radar (DPR) radar on board the Global Precipitation Measurement
Mission Dual-Precipitation Radar (GPM) are suitable for ground radar calibration.
Several studies volume-matched ground radar and GPM DPR Ku-band reflectivities for
the absolute calibration of ground radars, by applying different constraints and filters in
the volume-matching procedure. This study compares and evaluates volume-matching
thresholds and data filtering schemes for the Rizoelia, Larnaca (LCA) and Nata, Pafos (PFO)
radars of the Cyprus weather radar network from October 2017 till May 2023. Excluding
reflectivities below and within the melting layer with a 250 m buffer yielded consistent
results for both ground radars. The selected calibration schemes were combined, and
the resulting offsets were compared to stable radar parameters to identify stable calibration
periods. The consistency of the wet hydrological year October 2019 to September
2020 suggests that radar calibration results are prone to differences in meteorological conditions,
as scarce rainfall can result in insufficient data for reliable calibration. Future
work will incorporate disdrometer measurements and extend the analysis to quantitative
precipitation estimation.
are susceptible to calibration errors. Previous work demonstrated that observations from
the Ku-band Dual Polarization Radar (DPR) radar on board the Global Precipitation Measurement
Mission Dual-Precipitation Radar (GPM) are suitable for ground radar calibration.
Several studies volume-matched ground radar and GPM DPR Ku-band reflectivities for
the absolute calibration of ground radars, by applying different constraints and filters in
the volume-matching procedure. This study compares and evaluates volume-matching
thresholds and data filtering schemes for the Rizoelia, Larnaca (LCA) and Nata, Pafos (PFO)
radars of the Cyprus weather radar network from October 2017 till May 2023. Excluding
reflectivities below and within the melting layer with a 250 m buffer yielded consistent
results for both ground radars. The selected calibration schemes were combined, and
the resulting offsets were compared to stable radar parameters to identify stable calibration
periods. The consistency of the wet hydrological year October 2019 to September
2020 suggests that radar calibration results are prone to differences in meteorological conditions,
as scarce rainfall can result in insufficient data for reliable calibration. Future
work will incorporate disdrometer measurements and extend the analysis to quantitative
precipitation estimation.
Funding
The authors acknowledge the `EXCELSIOR’: ERATOSTHENES: EXcellence Research Centre for Earth Surveillance and Space-Based Monitoring of the Environment H2020 Widespread Teaming project (www.excelsior2020.eu, accessed on 10 March 2025). 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 acknowledge also the Department of Meteorology of the Republic of Cyprus for the provision of the X-band radar data. The authors wish to thank the five anonymous reviewers for their constructive comments that led to important improvements in the manuscript.
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