ABSTRACT

This project will examine the exchange of biological material between the Earth?s surface and atmosphere, and how this material may impact clouds and precipitation. Bioaerosols are airborne biological particles, such as pollen, fungal spores, and soil bacteria. Winds and thunderstorm updrafts loft biological material from the surface where they may serve as nuclei for the development of cloud droplets and ice crystals. The materials are then deposited back to the surface through precipitation, downdrafts, or gravitational settling. Despite this big picture view, the magnitude of exchange and the impact on cloud processes are still poorly understood. The research team will perform two field experiments using drones, balloons, instrumented towers, and surface instrumentation, combined with numerical modeling, to address a set of research questions related to bioaerosols. The result will be an improvement in weather and climate models and generation of new insight into the transport of allergens for human health purposes. A large set of students and early career researchers will be involved in the project, ensuring the training of the next generation of scientists.

The research team will study the fluxes of bioaerosols between the Earth?s surface and atmosphere and feedbacks between bioaerosols and storm microphysics, dynamics, and precipitation. The project objective is to quantitatively study the fluxes, concentrations, and identities of bioaerosols, specifically targeting intact pollen, sub-pollen particles, fungal spores and bacteria during convective storm updrafts, storm-generated cold pools, and quiescent conditions. Two field campaigns are planned, with flux tower measurements at National Ecological Observatory Network (NEON) sites, ground lab instrumentation, and drone-based sampling. Measurements will include fluorescent and total particle distributions, fluxes, particle characterization, chemical analysis and DNA sequencing, among others. Numerical modeling will make use of the Regional Atmospheric Modeling System (RAMS). Projected outcomes from the research are: 1) a comprehensive data set of aerosol data, including size distribution, flux and CCN/INP data for both total aerosol and bioaerosol subcategories for identified species, 2) determination of the vertical distribution of bacteria, fungi (spores and mycelia), and pollen in the atmosphere under varying meteorological conditions, and 3) development and implementation of a surface bioaerosol lofting parameterization in a widely-used open-source research model, development of a bioaerosol INP parameterization that can be readily implemented into wide range of numerical models, and an assessment of feedbacks between bioaerosols and storms and their implications for climate feedbacks.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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