Convective Storms Alter Local Bioaerosols and Ice Nucleating Particles Through Cold Pools and Rain
TERESA FELDMAN, Janeshta Fernando, Chamari Mampage, Claudia Mignani, Marina Nieto-Caballero, Thomas Hill, Brian Heffernan, Drew Juergensen, Christine Neumaier, Tyler Barbero, Charles Davis, Lexi Sherman, Ben Ascher, Jacob Escobedo, Nick Falk, Sean Freeman, Gabrielle Leung, Allie Mazurek, Daniel Veloso-Aguila, Leah Grant, Susan van den Heever, Russell Perkins, Paul DeMott, Sonia Kreidenweis, Elizabeth Stone, University of Iowa
Abstract Number: 490
Working Group: Bioaerosols
Abstract
Bioaerosols can significantly affect both human health and the climate, but further study is needed to understand how meteorology alters bioaerosol properties. To this end, bioaerosol concentrations, sizes, and types were measured in Northern Colorado as part of the BioAerosols and Convective Storms study. The first campaign (summer 2022) had drought-like conditions while the second (summer 2023) had near record rainfall. Offline samples were analyzed for bioaerosol tracers and ice nucleating particles (INPs), while online methods characterized fluorescent particles and INPs. Precipitation for both campaigns generally elevated bioaerosols based on fluorescent particle number concentrations, with an average increase of 3x pre-storm levels. Cold pools of air formed under thunderstorms had more varied impacts on bioaerosols, significantly enriching fluorescent particles for roughly half of the considered cases (n=56). Rain and cold pools mixed with rain generally led to a smaller particle size mode (1-4 µm) for supermicron fluorescent particles compared to isolated cold pools (2-10 µm), likely due to differences in bioaerosol emission and transport mechanisms. Despite no significant correlations during 2022 (n=29), changes in fluorescent particle concentrations correlated significantly (n=27, p<0.05) with cold pool perturbations of temperature (rs=-0.45), wind speed (rs=0.53), and relative humidity (rs=0.61) during 2023. These correlations indicate cold pools with stronger meteorological perturbations led to greater enrichment of local bioaerosols. Fungal spores were enriched more than pollen and gram-negative bacteria by convective storms, with pollen and endotoxin tracers often below detection. The fungal spore tracer primarily increased in particles 2.5-10 µm for samples during storms, correlating with increases in heat labile INPs at -15 °C for the same particle sizes (r=0.91, n=8, p<0.01). Convective storms significantly increase local bioaerosol and INPs through rain and cold pools, creating the potential for high exposure risks and storm ingestion of biological INPs.