Optical characterization of pollen types is possible using lidar measurements

We have defined lidar-derived properties (for example: size, shape, and amount) for pollen particles based on a four months campaign, which was performed during May to August 2016 in Vehmasmäki (~18 km from the city centre of Kuopio), in Eastern Finland. Twenty types of pollen were observed and identified by the traditional Burkard pollen sampler at ground level; among which, birch (Betula), pine (Pinus), spruce (Picea) and nettle (Urtica) pollen are most abundant, contributing more than 90 % of total pollen load, regarding number concentrations.

The ground-based multi-wavelength Raman polarization lidar PollyXT provides the vertical information of the atmosphere with the presence of pollen and other aerosols (e.g. dust, smoke, pollution). It allows the retrieval of pollen distribution in the atmosphere, using the novel algorithm. The shape information (depolarization ratio) of pure pollen particles was estimated for birch and pine pollen. This provides a good basis for pollen characterization and classification from profile measurements from lidar.

This novel method can also be applied to other aerosol mixtures (e.g. dust and non-dust aerosols) to retrieve the shape information (depolarization ratio) related to aerosol types.

More information:

Xiaoxia Shang, Finnish Meteorological Institute, tel. +358 50 3044824, xiaoxia.shang@fmi.fi

Shang, X., Giannakaki, E., Bohlmann, S., Filioglou, M., Saarto, A., Ruuskanen, A., Leskinen, A., Romakkaniemi, S., and Komppula, M.: Optical characterization of pure pollen types using a multi-wavelength Raman polarization lidar, Atmos. Chem. Phys., 20, 15323–15339, https://doi.org/10.5194/acp-20-15323-2020, 2020.