Skip to main content

Chemical and Morphological Analysis of Aerosols in the Stratosphere and Upper Troposphere and Their Ice Nucleation Potential

EMSL Project ID


Aerosols in the stratosphere and upper troposphere modify radiative forcing by scattering and absorbing solar radiation, as well as serving as ice nuclei to alter cloud formation process. Stratospheric aerosols also affect ozone chemistry by modulating the heterogenous reaction rates of halogen species on the particle surface. Radiative and chemical impacts of aerosols are greatly influenced by their chemical composition and morphology. While stratospheric aerosols have long been assumed to consist primarily of sulfuric acid/water solution droplets, sometimes with nitrate, observations and recent modeling studies show that organic components constitute a large part of stratospheric aerosols, especially in the lower stratosphere. Recent Australian and Canadian wildfire events also injected a large number of organic aerosols to the middle stratosphere. The chemical composition of the organic matter and the morphology of mixed organic/inorganic aerosols in the stratosphere and upper troposphere may play an important role in aerosol-light interaction, ice nucleation, as well as heterogeneous chemistry. Here, we propose to investigate the chemical composition, morphology, and ice nucleation propensity of aerosol particles collected in the stratosphere and upper troposphere using the NASA WB-57 high-altitude research aircraft. Offline measurements with microscopy and spectroscopy techniques will be conducted in the EMSL analytical facility. The results from these measurements are critical for quantifying: 1) the direct radiative effects of stratospheric aerosols, 2) the indirect radiative effects of tropopause region aerosols by affecting the nucleation of ice clouds, and 3) the heterogeneous halogen activation on the surface of organic-containing stratospheric aerosols.

Project Details

Project type
Large-Scale EMSL Research
Start Date
End Date


Principal Investigator

Frank Keutsch
Harvard University


John Dykema
Harvard University