Ice-nucleating Particle Characteristics and Relation to Bioaerosols in Air and in Precipitation at a Semi-arid Grassland Site

Claudia Mignani, PAUL DEMOTT, Thomas C. J. Hill, Marina Nieto-Caballero, Noelle Bryan, Alexei Kiselev, Nurun Nahar Lata, Swarup China, Teresa Feldman, Chamari Mampage, Kathryn Moore, Amy P. Sullivan, Ben Ascher, Nick Falk, Sean Freeman, Gabrielle Leung, Allie Mazurek, Christine Neumaier, Thomas Leisner, Susan van den Heever, Leah Grant, Elizabeth Stone, Russell Perkins, Sonia Kreidenweis, et al., Colorado State University

     Abstract Number: 533
     Working Group: Aerosol-Ecosystem Interactions

Abstract
Biological ice-nucleating particles (INPs) are released into the atmosphere from soils, water, and plants. This subset of bioaerosols catalyze the formation of ice in clouds at temperatures modestly below 0°C. Precipitation-stimulated release is a mechanism observed in many ecosystems. Here, we seek to understand this process using observations at the National Science Foundation (NSF) National Ecological Observing Network Central Plains Experimental Range, a semi-arid shortgrass site in Northeast Colorado. The CPER site is representative of regions of the North American Great Plains, an area that experiences episodes of severe weather, including heavy rain, large hail, and strong, low-level winds associated with convective cold pools.

We present results from collaborative studies of the BioAerosol and Convective Storms Phase I (BACS-I) campaign and the NSF Biology Integration Institute Regional OneHealth Aerobiome Discovery Network (BROADN), occurring from May 23 to June 17, 2022. Together, these studies examined environmental and storm-related bioaerosol release and feedbacks of bioaerosols on storm development. A Wideband Integrated Bioaerosol Sensor was run continuously to measure fluorescent aerosol particles, and those observations indicated that precipitation, air mass boundary passages, and relative humidity cycles influenced the abundance of fluorescent biological aerosol particle types. Rain was collected during three events. Aerosol particles were sampled before, during and after rain events with a high-volume filter sampler, polycarbonate filters and a size-resolved impactor. Filters and precipitation samples were processed to measure and compare the atmospheric and within-precipitation concentrations of INPs. INP concentrations in precipitation are consistent with INP concentrations in air measured prior to precipitation events. Enhancement of biological INPs in air is noted following precipitation. Scanning electron microscopy (SEM) techniques are used to determine the chemical composition and morphology of single particles and, via environmental-SEM, INPs. Future studies will link amplicon and metagenomic sequencing to bioaerosol and INP responses to precipitation.