Large hemispheric difference in nucleation mode aerosol concentrations in the lowermost stratosphere at mid- and high latitudes Journal Article uri icon



  • Abstract. The details of aerosol processes and size distributions; in the stratosphere are important for both heterogeneous chemistry and; aerosol–radiation interactions. Using in situ, global-scale measurements of; the size distribution of particles with diameters > 3 nm from the; NASA Atmospheric Tomography Mission (ATom), we identify a mode of aerosol; smaller than 12 nm in the lowermost stratosphere (LMS) at mid- and high; latitudes. This mode is substantial only in the Northern Hemisphere (NH); and was observed in all four seasons. We also observe elevated SO2, an; important precursor for new particle formation (NPF) and growth, in the NH; LMS. We use box modelling and thermodynamic calculations to show that NPF; can occur in the LMS conditions observed on ATom. Aircraft emissions are; shown as likely sources of this SO2, as well as a potential source of; nucleation mode particles directly emitted by or formed in the plume of the; engines. These nucleation mode particles have the potential to grow to; larger sizes and to coagulate with larger aerosol, affecting heterogeneous; chemistry and aerosol–radiation interactions. Understanding all sources and; characteristics of stratospheric aerosols is important in the context of; anthropogenic climate change as well as proposals for climate intervention; via stratospheric sulfur injection. This analysis not only adds to the,; currently sparse, observations of the global impact of aviation, but also; introduces another aspect of climate influence, namely a size distribution; shift of the background aerosol distribution in the LMS.;

publication date

  • June 15, 2021

Full Author List

  • Williamson CJ; Kupc A; Rollins A; Kazil J; Froyd KD; Ray EA; Murphy DM; Schill GP; Peischl J; Thompson C

Other Profiles

Additional Document Info

start page

  • 9065

end page

  • 9088


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