Profiling pollen and biomass burning particles over Payerne, Switzerland using laser-induced fluorescence lidar and in situ techniques during the 2023 PERICLES campaign

Abstract. Vertical profiles of pollen and biomass burning particles were obtained at a semi-rural site at the MeteoSwiss station near Payerne (Switzerland) using a novel multi-channel elastic-fluorescence lidar combined with in situ measurements during the spring 2023 wildfires and pollination season during the PERICLES (PayernE lidaR and Insitu detection of fluorescent bioaerosol and dust partiCLES and their cloud impacts) campaign. Pollen particles were detected near ground (up to 2 km height), showing strong fluorescence backscatter coefficients b_F at 355 nm (b_F ~2 x 10^-4 Mm^-1sr^-1 to 8 x 10^-4 Mm^-1sr^-1). Smoke plumes from Canada and Germany were detected at higher altitudes (3–5 km) and showed lower b_F values compared to those from pollen particles near ground. In situ measurements and in vivo fluorescence spectra were used to classify pollen particles near ground. Ice nucleating particle (INP) concentrations relevant for mixed-phase clouds showed high concentrations at warm temperatures, characteristic of the contribution of biological particles to the INP population. This was further supported by the correlation of INPs at –14 °C with WIBS_ABC particles, indicating a contribution from fluorescent biological aerosol particles, while INPs at –20 °C were more strongly linked to coarse-mode dust. The analysis of b_F values across two European LIF lidar stations revealed that aged air masses containing smoke particles can show a ~50 % reduction of these values during their transport in the free troposphere (3–5 km) possibly due to photochemical aging and mixing with other non-fluorescent particles.