Datasets used in Gatou et al. (2026) "Vertical distribution, optical characterization and automated classification of airborne pollen from in situ measurements"

Description

Technical info

Airborne pollen concentrations were measured using a Burkard 7-day recording volumetric air sampler operated at 4 m above ground level. The sampler draws air through a 14 mm × 2 mm orifice at a flow rate of 10 L min⁻¹. Collected samples were analyzed by light microscopy and pollen grains were identified according to their morphological characteristics. Pollen concentrations have a temporal resolution of 2 h and are expressed as pollen grains m⁻³.

PS2 optical particle sensors were operated at different measurement heights. The sensors draw air at a flow rate of 0.7 L min⁻¹ and used a 790 nm laser diode and two scattered-light detection channels, Ppol and Spol, to characterize individual particles. Ppol is a relative measure related to particle size, while Spol is the scattered-light intensity measured through a polarization filter perpendicular to the polarization of the incident light. The depolarization degree is calculated from Ppol and Spol and provides a relative index related to particle shape. The supplied PS2 datasets contain measurements averaged over 10 min intervals. 

Cloud Droplet Analyzer (CDA) measurements were used to characterize particle number concentration, particle mass concentration, and mean particle diameter. Separate datasets are provided for the total measured particle population and for particles within the 20–100 µm size range. The 20–100 µm measurements were used as an independent estimate of coarse-particle concentrations during the PS2 intercomparison related to the size range of pollen particles.

Aerosol particle size distributions were measured using a NanoScan Scanning Mobility Particle Sizer (model 3910, TSI Incorporated, USA) and an Optical Particle Sizer (model 3330, TSI Incorporated, USA). The NanoScan measured particle mobility diameters from approximately 10 to 420 nm, while the OPS measured optical particle diameters from approximately 0.3 to 10 µm. The distributions were processed and merged following the methodology described by Filioglou et al. (2025).

Modelled pollen concentrations were obtained from the SILAM atmospheric composition model developed by FMI. The supplied dataset contains hourly pollen number concentration profiles for March–August 2024 at 10 atmospheric layers.

Series information

Dataset information

Hirst-type pollen measurements

The files Burkard_Vehmasmaki_2021.csv, Burkard_Vehmasmaki_2022.csv, Burkard_Vehmasmaki_2023.csv, and Burkard_Vehmasmaki_2024.csv contain 2 h airborne pollen concentrations measured with the Hirst-type volumetric sampler.

Each file contains the local measurement time, corresponding UTC time, total pollen concentration, and taxon-specific pollen concentrations. The timestamp represents the midpoint of each 2 h sampling interval.

Units: total and taxon-specific pollen concentrations are expressed as pollen grains m⁻³. Time is provided as date and time. Missing measurements are represented by NaN.

PS2 optical particle measurements

The PS2 CSV files contain 10 min averaged optical particle measurements from the individual PS2 instruments and measurement heights. Each file contains the midpoint timestamp of the averaging interval, particle number concentration, mean Ppol, mean Spol, mean depolarization degree (Depodeg) and number of detected particles (Sum). PS2 optical particle sensors were operated at 4, 115 and 272 m above ground level, depending on the measurement period. The corresponding measurement heights and instrument identifiers are indicated in the individual dataset filenames. 

Units: particle number concentration is expressed as particles m⁻³; Ppol and Spol are reported in relative units; Depodeg is dimensionless; Sum represents the number of detected particles (count); and the averaging period is 10 min.

Cloud Droplet Analyzer (CDA) measurements

The file CDA_Vehmis2023_tot.csv contains CDA measurements for the total measured particle number at Vehmasmäki in 2023. The dataset contains measurement time, total particle number concentration, total particle mass concentration, and mean particle diameter.

Units: total particle number concentration is expressed as particles cm⁻³, total particle mass concentration as mg m⁻³, and mean particle diameter as µm.

The file CDA_Vehmis2023_pollen.csv contains the corresponding CDA measurements for particles within the 20–100 µm size range. This size range was used to characterize particles corresponding to the typical size range of airborne pollen and to provide an independent comparison with the PS2 measurements.

Units: particle number concentration is expressed as particles cm⁻³, particle mass concentration as mg m⁻³, and mean particle diameter as µm.

The CDA data are retained in their original units without additional unit conversion.

NanoScan–OPS aerosol particle size distributions

The file NS_OPS_particle_size_distribution.csv contains the processed merged NanoScan–OPS aerosol particle size distributions. The processed dataset covers particle diameters from approximately 11.5 nm to 8.97 µm and contains hourly measurements. Missing measurements are represented by NaN.

The accompanying file NS_OPS_size_bins.csv contains information describing the particle-size bins used in the main dataset.

Units: particle-diameter midpoint (dp_mid) is expressed as µm; logarithmic (log10) particle-size bin width (dlogDp) is dimensionless; particle number size distribution (dNdlogDp) is expressed as particles cm⁻³ per logarithmic particle-diameter interval; total particle number concentration (N_tot) is expressed as particles cm⁻³; particle volume size distribution (dVdlogDp) is expressed as µm³ cm⁻³ per logarithmic particle-diameter interval; and total particle volume concentration (V_tot) is expressed as µm³ cm⁻³.

The particle number and volume concentrations are related to their respective size distributions according to N_tot = Σ [(dN/dlogDp) × dlogDp] and V_tot = Σ [(dV/dlogDp) × dlogDp].

SILAM pollen data

The file SILAM_Kuopio_March-August_2024.csv contains hourly SILAM pollen number concentration profiles for the Kuopio area during March–August 2024.

The dataset includes alder, birch, grass, hazel, mugwort, olive, and ragweed pollen concentrations. Data are provided for 10 atmospheric layers with mid-heights of 12.5, 50, 125, 275, 575, 1150, 2125, 3725, 5725, and 7725 m. Each row represents one UTC timestamp and one atmospheric model layer and additionally provides the model-layer thickness and geographical coordinates of the extracted model location.

Units: pollen number concentrations are expressed as pollen grains m⁻³; model-layer mid-height and layer thickness are expressed in m; longitude is expressed in degrees east (°E) and latitude in degrees north (°N). The temporal resolution is 1 h, and timestamps are provided in UTC.