Technical Note: Evaporation of polar stratospheric cloud particles, in situ, in a heated inlet T. Eidhammer and T. Deshler University of Wyoming, Department of Atmospheric Science, USA
Abstract. In December 2001 and 2002 in situ aerosol measurements were
made from balloon-borne platforms within polar stratospheric clouds
(PSC) which contained particles of supercooled ternary solution
(STS), nitric acid trihydrate (NAT) and ice. Particle size
and number concentrations were
measured with two optical particle counters. One of these included
an ~80cm inlet heated to K to evaporate the
PSC particles and thus to obtain measurements, within PSCs, of the
size distribution of the particles upon which the PSCs condensed.
These measurements are compared to models, described here, that
calculate the evaporation of PSC particles at and
for an inlet transition time of about 0.1s.
The modeled evaporation for STS agrees well with the
measurements. For NAT the modeled evaporation is less than the
evaporation measured. The primary uncertainty concerns the phase and
morphology of NAT particles as they are brought to temperatures
>50K above equilibrium temperatures for NAT at stratospheric partial
pressures. The slow evaporation of NAT in heated inlets could be
used to identify a small NAT component within a mixed phase PSC
dominated by STS.
Citation: Eidhammer, T. and Deshler, T.: Technical Note: Evaporation of polar stratospheric cloud particles, in situ, in a heated inlet, Atmos. Chem. Phys., 5, 97-106, doi:10.5194/acp-5-97-2005, 2005.