Absolute calibrated signals at 532 and 1064 nm and thedepolarization ratio from a multiwavelength lidar are used tocategorize primary aerosol but also clouds in high temporal andspatial resolution. Automatically derived particle backscattercoefficient profiles in low temporal resolution (30 min) areapplied to calibrate the lidar signals. From these calibrated lidarsignals, new atmospheric parameters in temporally high resolution(quasi-particle-backscatter coefficients) are derived. By usingthresholds obtained from multiyear, multisite EARLINET (European Aerosol Research Lidar Network) measurements,four aerosol classes (small; large, spherical; large, non-spherical;mixed, partly non-spherical) and several cloud classes (liquid, ice)are defined. Thus, particles are classified by their physical features(shape and size) instead of by source.The methodology is applied to 2 months of continuousobservations (24 h a day, 7 days a week) with themultiwavelength-Raman-polarization lidar Polly duringthe High-Definition Clouds and Precipitation foradvancing Climate Prediction (HD(CP)) Observational PrototypeExperiment (HOPE) in spring 2013. Cloudnet equipment was operatedcontinuously directly next to the lidar and is used for comparison.By discussing three 24 h case studies, it is shown that theaerosol discrimination is very feasible and informative and givesa good complement to the Cloudnet target categorization. Performingthe categorization for the 2-month data set of the entire HOPEcampaign, almost 1 million pixel (5 min × 30 m)could be analysed with the newly developed tool. We find that themajority of the aerosol trapped in the planetary boundarylayer (PBL) was composed of small particles as expected for a heavily populatedand industrialized area. Large, spherical aerosol was observed mostlyat the top of the PBL and close to the identified cloud bases,indicating the importance of hygroscopic growth of the particles athigh relative humidity. Interestingly, it is found that on severaldays non-spherical particles were dispersed from the ground into the atmosphere.
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