Validation of EarthCARE CPR reflectivity using the ACTRIS cloud radar network
Abstract
The Earth Cloud, Aerosol, and Radiation Explorer (EarthCARE) satellite carries a cloud profiling radar (CPR) designed to observe global cloud properties. In this study, we assess the calibration of CPR reflectivity profiles by comparing them with seven calibrated ground-based cloud radars from the European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). We compare the statistics of ice cloud reflectivities observed from space and from each ground site. The CPR dataset includes all observations within a 200 km radius of each site, while the ground-based dataset comprises vertical profiles collected during the same time period. For this study, the CPR and ACTRIS data were compared on a period spanning from July 2024 to November 2025. By analysing the differences in reflectivity statistics, we estimate the calibration bias between CPR and each site. To ensure robustness, we implement a method to select height bins with comparable reflectivity statistics, excluding uncorrelated observations that could contaminate the results. The reliability of our bias estimates is validated through closure: each ground radar has been calibrated using the same reference, and the independently derived space-versus-ground biases obtained across sites are consistent. Our methodology also provides uncertainty estimates for the reflectivity biases and explores the time sampling required for reliable comparisons. Based on the comparisons from the seven ground-sites, we find that the bias in the EarthCARE L2a reflectivity product is of dB, confirming the high quality of the satellite's calibration. This robust statistical approach, validated with calibrated radars, establishes EarthCARE as a potential reference for calibrating ACTRIS and other ground-based sites in the future.
Related
- Airborne Validation of Cloud Spatial Properties from the ATLID Instrument on EarthCARE
- A preliminary analysis of tropical anvil-cloud dynamics in EarthCARE
- EarthCARE Observations of Vertical Motion and Cloud Microphysical Structure in Tropical Cyclones
- Satellite–Ground Intercomparison between EarthCARE/ATLID and the China Aerosol Raman Lidar Network (CARLNET): Part I. Case Studies
- Persistent EarthCARE underflight studies of the ITCZ and organized convection (PERCUSION): contribution to EarthCARE validation
BibTeX
@article{feuillard2026validation,
title = {{Validation of EarthCARE CPR reflectivity using the ACTRIS cloud radar network}},
author = {Nathan Feuillard and Felipe Toledo Bittner and Lukas Pfitzenmaier and Jean-François Ribaud and Julien Delanoë and Martial Haeffelin and Jean-Charles Dupont},
journal = {Atmospheric Measurement Techniques},
year = {2026},
month = sep,
doi = {10.5194/amt-19-6075-2026},
url = {https://hal.science/hal-05529628v2},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Validation of EarthCARE CPR reflectivity using the ACTRIS cloud radar network
AU - Nathan Feuillard
AU - Felipe Toledo Bittner
AU - Lukas Pfitzenmaier
AU - Jean-François Ribaud
AU - Julien Delanoë
AU - Martial Haeffelin
AU - Jean-Charles Dupont
PY - 2026
DA - 2026/09/24
JO - Atmospheric Measurement Techniques
DO - 10.5194/amt-19-6075-2026
UR - https://hal.science/hal-05529628v2
AB - The Earth Cloud, Aerosol, and Radiation Explorer (EarthCARE) satellite carries a cloud profiling radar (CPR) designed to observe global cloud properties. In this study, we assess the calibration of CPR reflectivity profiles by comparing them with seven calibrated ground-based cloud radars from the European Aerosol, Clouds and Trace Gases Research Infrastructure (ACTRIS). We compare the statistics of ice cloud reflectivities observed from space and from each ground site. The CPR dataset includes all observations within a 200 km radius of each site, while the ground-based dataset comprises vertical profiles collected during the same time period. For this study, the CPR and ACTRIS data were compared on a period spanning from July 2024 to November 2025. By analysing the differences in reflectivity statistics, we estimate the calibration bias between CPR and each site. To ensure robustness, we implement a method to select height bins with comparable reflectivity statistics, excluding uncorrelated observations that could contaminate the results. The reliability of our bias estimates is validated through closure: each ground radar has been calibrated using the same reference, and the independently derived space-versus-ground biases obtained across sites are consistent. Our methodology also provides uncertainty estimates for the reflectivity biases and explores the time sampling required for reliable comparisons. Based on the comparisons from the seven ground-sites, we find that the bias in the EarthCARE L2a reflectivity product is of dB, confirming the high quality of the satellite's calibration. This robust statistical approach, validated with calibrated radars, establishes EarthCARE as a potential reference for calibrating ACTRIS and other ground-based sites in the future.
SN - 1867-1381
SN - 1867-8548
ER -