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Biological aerosols in the atmosphere and links to ice nucleating particles and precipitation
Bioaerosols are relevant for public health and may play an important role in the climate system, but their atmospheric abundance, properties, and sources are not well understood. Through a series of ground-based measurements, with emphasis on real-time fluorescence and also including microscopy and droplet freezing techniques, we show that bioparticles are often closely correlated with atmospheric ice nucleating particles (INP). We also show that in some locations, but not all, the concentration of airborne biological particles and their molecular tracers increase significantly during rain. The peak in bioparticle concentration is typically ~3 µm and the greatest rain-induced increase of bioparticles and INP occurred in the size range of 2-6 µm, which is characteristic for bacterial aggregates and fungal spores. Medium-term measurements (10-18 months) of fluorescent bioparticles show seasonal increases during summer and fall, with reductions of more than an order of magnitude during winter. Our findings suggest that atmospheric bioaerosols, INP, and rainfall are often tightly coupled and that daily and seasonal patterns in bioaerosol emission are broadly consistent and predictable. These findings support recent suggestions that biogenic aerosols are critical components to the hydrological cycle in certain ecosystems and could act as catalysts for regional-scale biogeochemical reactors that propagate precipitation and plant growth. As an aspect of the talk I will also introduce a new handheld instrument we are developing to look at fluorescent spectra of individual particles collected onto a substrate, but at much lower cost than existing particle spectrometers.
Part of the 2016 Earth Planetary and Space Sciences Institute (EPSSI) Seminar Series
Annual seminar series on topics related to Earth Planetary and Space Sciences and course UN 4000 REMOTE SENSING.
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