Journal article

An aerosol chamber investigation of the heterogeneous ice nucleating potential of refractory nanoparticles

Saunders R, Möhler O, Schnaiter M, Benz S, Wagner R, Saathoff H, Connolly P, Burgess R, Murray B, Gallagher M, Wills R, Plane J ...see all

Atmospheric Chemistry and Physics, vol. 10, issue 3 (2010) pp. 1227-1247

  • 36

    Readers

    Mendeley users who have this article in their library.
  • 27

    Citations

    Citations of this article.
Sign in to save reference

Abstract

Nanoparticles of iron oxide (crystalline and amor-phous), silicon oxide and magnesium oxide were investi-gated for their propensity to nucleate ice over the temper-ature range 180–250 K, using the AIDA chamber in Karl-sruhe, Germany. All samples were observed to initiate ice formation via the deposition mode at threshold ice super-saturations (RHi thresh) ranging from 105% to 140% for temperatures below 220 K. Approximately 10% of amorphous Fe 2 O 3 particles (modal diameter = 30 nm) generated in situ from a photochemical aerosol reactor, led to ice nucleation at RHi thresh = 140% at an initial chamber temperature of 182 K. Quantitative analysis using a singular hypothesis treatment provided a fitted function [n s (190K) = 10 (3.33⇥s ice)+8.16 ] for the variation in ice-active surface site density (n s :m 2) with ice saturation (s ice) for Fe 2 O 3 nanoparticles. This was im-plemented in an aerosol-cloud model to determine a pre-dicted deposition (mass accommodation) coefficient for wa-ter vapour on ice of 0.1 at temperatures appropriate for the upper atmosphere. Classical nucleation theory was used to determine representative contact angles (✓) for the different particle compositions. For the in situ generated Fe 2 O 3 parti-cles, a slight inverse temperature dependence was observed with ✓ = 10.5 at 182 K, decreasing to 9.0 at 200 K (com-pared with 10.2 and 11.4 respectively for the SiO 2 and MgO particle samples at the higher temperature). These observations indicate that such refractory nanopar-ticles are relatively efficient materials for the nucleation of ice under the conditions studied in the chamber which cor-respond to cirrus cloud formation in the upper troposphere. The results also show that Fe 2 O 3 particles do not act as Correspondence to: J. M. C. Plane (j.m.c.plane@leeds.ac.uk) ice nuclei under conditions pertinent for tropospheric mixed phase clouds, which necessarily form above ⇠233 K. At the lower temperatures (

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Get full text

Authors

  • R. W. Saunders

  • O. Möhler

  • M. Schnaiter

  • S. Benz

  • R. Wagner

  • H. Saathoff

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free