PNNL

Abstract

The spatial distribution of ambient aerosol particles significantly impacts aerosol-radiation-cloud interactions, which contribute to the largest uncertainty in global anthropogenic radiative forcing estimations. However, the atmospheric boundary layer and lower free troposphere have not been adequately sampled in terms of temporospatial resolution, hindering a comprehensive characterization of various atmospheric processes and impeding our understanding of the Earth system. To address this research data gap, we have leveraged the development of uncrewed aerial systems (UAS) and advanced measurement techniques to obtain mesoscale spatial data on aerosol microphysical and optical properties around the U.S. Southern Great Plains (SGP observatory). Our study also benefits from state-of-the-art laboratory facilities that include 3-dimensional molecular imaging techniques enabled by secondary ion mass spectrometry coupled with nanogram-level chemical composition analysis via micronebulization aerosol mass spectrometry. Through our investigations, we have identified the prominent role of organic-enriched nanometer layers located at the surface of aerosol particles in determining profiles of aerosol optical and hygroscopic properties over the SGP observatory. Furthermore, we have developed a framework for observation-modeling integration, enabling an examination of how various assumptions for the organic-inorganic components mixing state, inferred from chemical analysis, affect clouds and radiation in observation-constrained model simulations. By integrating observational constraints derived from chemical analysis of the aerosol surface with in-situ UAS observations, we have improved the agreement between predicted clouds and ground-based cloud lidar measurements. This UAS-model-laboratory integration exemplifies how these new advanced capabilities can significantly enhance our understanding of aerosol-radiation-cloud interactions.