We are pleased to share a new publication supported by COST Action EARLICOST (CA24135).

“Validation of ceilometer aerosol profile retrievals using sun–sky photometer and balloon-borne in situ measurements” — published in Atmospheric Chemistry and Physics (Copernicus/EGU).

This study evaluates the capability of operational ceilometers to retrieve aerosol backscatter and extinction profiles through a comprehensive evaluation against independent reference datasets.

Key highlights from the study:

• Two retrieval approaches are compared: the traditional Klett–Fernald backward inversion and a forward iterative method with independent calibration, evaluated against synergistic GRASPpac products and balloon-borne COBALD in situ measurements
• Observations were collected at three European stations with contrasting aerosol regimes: Granada (Spain), Payerne (Switzerland), and Lindenberg (Germany) during 2019 – 2020
• The forward iterative approach generally provides better agreement with reference datasets than the Klett–Fernald backward approach
• Under high aerosol load conditions, particularly during coarse-mode-dominated events, the forward retrieval reduces AOD uncertainties by ~50% and achieves root-mean-square errors comparable to those reported in previous validation studies
• The forward method maintains consistent accuracy throughout the troposphere, whereas the backward approach exhibits altitude-dependent biases, especially within dust layers
• COBALD balloon-borne backscatter measurements confirm that the forward retrieval reproduces observed aerosol structures within 10% – 30% deviation

The results support the integration of forward iterative ceilometer retrievals into existing observational networks such as E-Profile and ICENET, enhancing regional and continental aerosol monitoring capabilities.

Read the full paper here: https://doi.org/10.5194/acp-26-10255-2026