Ceilometer aerosol profiling versus Raman lidar in the frame of the INTERACT campaign of ACTRIS

摘要

Despite their differences from more advanced and more powerful lidars, thelow construction and operation cost of ceilometers (originally designed forcloud base height monitoring) has fostered their use for the quantitativestudy of aerosol properties. The large number of ceilometers availableworldwide represents a strong motivation to investigate both the extent towhich they can be used to fill in the geographical gaps between advancedlidar stations and also how their continuous data flow can be linked toexisting networks of the more advanced lidars, like EARLINET (EuropeanAerosol Research Lidar Network).In this paper, multi-wavelength Raman lidar measurements are used toinvestigate the capability of ceilometers to provide reliable informationabout atmospheric aerosol properties through the INTERACT (INTERcomparisonof Aerosol and Cloud Tracking) campaign carried out at the CNR-IMAAAtmospheric Observatory (760 m a.s.l., 40.60° N, 15.72° E), in the frameworkof the ACTRIS (Aerosol Clouds Trace gases Research InfraStructure) FP7project. This work is the first time that three different commercialceilometers with an advanced Raman lidar are compared over a period of 6 months. The comparison of the attenuated backscatter coefficient profilesfrom a multi-wavelength Raman lidar and three ceilometers (CHM15k, CS135s,CT25K) reveals differences due to the expected discrepancy in the signal to noise ratio (SNR) butalso due to changes in the ambient temperature on the short and mid-termstability of ceilometer calibration. Therefore, technological improvementsare needed to move ceilometers towards operational use in the monitoring ofatmospheric aerosols in the low and free troposphere.