Concurrent SwisensPoleno Jupiter and WIBS-5 Measurements of Atmospheric Bioaerosols at the Sonnblick Observatory

We present concurrent measurements of atmospheric bioaerosols at the Sonnblick Observatory obtained with a SwisensPoleno Jupiter and a WIBS-5 from DROPLET ENVEA Group between August and November 2024. The observatory is located directly at the top of Mount “Hoher Sonnblick” (3106 m a.s.l.) and serves as an ACTRIS national facility for in-situ aerosol observations and as European Center for Cloud ambient INTercomparison (ECCINT). Because of its high altitude, the station is often immersed in clouds, making it suitable for studying aerosol–cloud interactions. Bioaerosols are known to act as ice-nucleating particles at relatively high temperatures, but their occurrence in the atmosphere is still poorly understood. Therefore, assessing the presence of bioaerosols at this high alpine site is of particular interest.

During the late summer 2024 ECCINT intercomparison campaign, the WIBS-5  was operated alongside the permanently installed SwisensPoleno Jupiter. Both instruments detect fluorescence signals of single particles, but exhibit differences in excitation sources and detection wavebands. Also, the SwisensPoleno Jupiter uses a particle concentrator to enhance the sampling of larger particles (≥10 µm) and additionally provides holographic images. In contrast, without a concentrator, the WIBS-5 primarily samples smaller particles down to 500 nm.

In this presentation, we first present data from both instruments independently and examine observed bioaerosol patterns in relation to other aerosol properties and meteorological conditions. For the WIBS-5, we apply the common classification scheme dividing particles into A, B, C classes and their combinations, while for the SwisensPoleno Jupiter we use a deterministic classification roughly separating particles into pollen-, spore-, plant-debris-, dust-like, and other fluorescent types.

In the second step, we compare data from the two instruments to illustrate how differences in size sensitivity and detection approach relate to observed bioaerosol patterns. We also discuss how the instruments can be used complementarily to provide a broader view of bioaerosol presence in the atmosphere.