title: Ice residual properties in mixed-phase clouds at the high-alpine Jungfraujoch site.
abstract: Ice residual (IR) and total aerosol properties were measured in mixed-phase clouds (MPCs) at the high-alpine Jungfraujoch research station. Black carbon (BC) content and coating thickness of BC-containing particles were determined using single-particle soot photometers. The ice activated fraction (IAF), derived from a comparison of IR and total aerosol particle size distributions, showed an enrichment of large particles in the IR, with an increase in the IAF from values on the order of 10-4to 10-3for 100 nm (diameter) particles to 0.2 to 0.3 for 1 μm (diameter) particles. Nonetheless, due to the high number fraction of submicrometer particles with respect to total particle number, IR size distributions were still dominated by the submicrometer aerosol. A comparison of simultaneously measured number size distributions of BC-free and BC-containing IR and total aerosol particles showed depletion of BC by number in the IR, suggesting that BC does not play a significant role in ice nucleation in MPCs at the Jungfraujoch. The potential anthropogenic climate impact of BC via the glaciation effect in MPCs is therefore likely to be negligible at this site and in environments with similar meteorological conditions and a similar aerosol population. The IAF of the BC-containing particles also increased with total particle size, in a similar manner as for the BC-free particles, but on a level 1 order of magnitude lower. Furthermore, BC-containing IR were found to have a thicker coating than the BC-containing total aerosol, suggesting the importance of atmospheric aging for ice nucleation.
authors.affiliation: Laboratory of Atmospheric Chemistry Paul Scherrer Institute Villigen Switzerland; Now at Department of Meteorology Stockholm University Stockholm Sweden.
authors.forename: Piotr
authors.initials: P
authors.lastname: Kupiszewski
authors.affiliation: Laboratory of Atmospheric Chemistry Paul Scherrer Institute Villigen Switzerland; Laboratoire de Glaciologie et Géophysique de l'Environnement Université Grenoble Alpes/CNRS Grenoble France; Now at Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research Bremerhaven Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Zanatta
authors.affiliation: Leibniz Institute for Tropospheric Research Leipzig Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Mertes
authors.affiliation: Institute of Meteorology and Climate Research Karlsruhe Institute of Technology Karlsruhe Germany.
authors.forename: Paul
authors.initials: P
authors.lastname: Vochezer
authors.affiliation: Centre for Atmospheric Science, SEAES University of Manchester Manchester UK.
authors.forename: Gary
authors.initials: G
authors.lastname: Lloyd
authors.affiliation: Particle Chemistry Department Max Planck Institute for Chemistry Mainz Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Schneider
authors.affiliation: Leibniz Institute for Tropospheric Research Leipzig Germany.
authors.forename: Ludwig
authors.initials: L
authors.lastname: Schenk
authors.affiliation: Institute of Meteorology and Climate Research Karlsruhe Institute of Technology Karlsruhe Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Schnaiter
authors.affiliation: Laboratory of Atmospheric Chemistry Paul Scherrer Institute Villigen Switzerland.
authors.forename: Urs
authors.initials: U
authors.lastname: Baltensperger
authors.affiliation: Laboratory of Atmospheric Chemistry Paul Scherrer Institute Villigen Switzerland; Now at Institute for Aerosol and Sensor Technology University of Applied Sciences Windisch Switzerland.
authors.forename: Ernest
authors.initials: E
authors.lastname: Weingartner
authors.affiliation: Laboratory of Atmospheric Chemistry Paul Scherrer Institute Villigen Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Gysel
keywords: black carbon; heterogeneous ice nucleation; ice residuals; mixed‐phase clouds