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. A quantitative comparison study for Raman lidar andceilometer observations, and for model simulations of mass concentrationestimates of smoke particles is presented. Layers of biomass burning aerosolparticles were observed in the lower troposphere, at 2 to 5 km height on 4to 6 June 2019, over Kuopio, Finland. These long-range-transported smokeparticles originated from a Canadian wildfire event. The most pronouncedsmoke plume detected on 5 June was intensively investigated. Opticalproperties were retrieved from the multi-wavelength Raman polarization lidarPollyXT. Particle linear depolarization ratios (PDRs) of this plume weremeasured to be 0.08±0.02 at 355 nm and 0.05±0.01 at 532 nm,suggesting the presence of partly coated soot particles or particles thathave mixed with a small amount of dust or other non-spherical aerosol type.The layer-mean PDR at 355 nm (532 nm) decreased during the day from∼0.11 (0.06) in the morning to ∼0.05 (0.04) inthe evening; this decrease with time could be linked to the particle agingand related changes in the smoke particle shape properties. Lidar ratioswere derived as 47±5 sr at 355 nm and 71±5 sr at 532 nm. Acomplete ceilometer data processing for a Vaisala CL51 ceilometer is presented froma sensor-provided attenuated backscatter coefficient to particle massconcentration (including the water vapor correction for high latitude forthe first time). Aerosol backscatter coefficients (BSCs) were measured atfour wavelengths (355, 532, 1064 nm from PollyXT and 910 nm fromCL51). Two methods, based on a combined lidar and sun-photometer approach,are applied for mass concentration estimations from both PollyXT andthe ceilometer CL51 observations. In the first method, no. 1, we usedconverted BSCs at 532 nm (from measured BSCs) by corresponding measuredbackscatter-related Ångström exponents, whereas in the second method, no. 2, we used measured BSCs at each wavelength independently. A differenceof ∼12 % or ∼36 % was found betweenPollyXT and CL51 estimated mass concentrations using method no. 1 orno. 2, showing the potential of mass concentration estimates from a ceilometer. Ceilometer estimations have an uncertainty of ∼50 % in the mass retrieval, but the potential of the data lies in the greatspatial coverage of these instruments. The mass retrievals were comparedwith the Modern-Era Retrospective analysis for Research and Applications,version 2 (MERRA-2) meteorological and aerosol reanalysis. The inclusion ofdust (as indicated by MERRA-2 data) in the retrieved mass concentration isnegligible considering the uncertainties, which also shows that ceilometerobservations for mass retrievals can be used even without exact knowledge of the composition of the smoke-dominated aerosol plume in the troposphere.

atmospheric measurement techniques

Mass concentration estimates of long-range-transported Canadian biomass burning aerosols from a multi-wavelength Raman polarization lidar and a ceilometer in Finland