Composition analysis of liquid particles in the Arctic stratosphere under synoptic conditions
Other literature type
(issn: 1680-7324, eissn: 1680-7324)
Synoptic scale polar stratospheric clouds (PSCs) that formed
without the presence of mountain lee waves were observed in early
December 2002 from Kiruna/Sweden using balloon-borne instruments.
The physical, chemical, and optical properties of the particles
were measured. Within the PSC solid particles existed whenever the
temperature was below the equilibrium temperature for nitric acid
trihydrate and liquid particles appeared when the temperature fell
below an even lower threshold about 3 K above the frost point with
solid particles still present. The correlation of liquid
supercooled ternary solution aerosols with local temperatures is a
pronounced feature observed during this flight; average molar
ratios H<sub>2</sub>O/HNO<sub>3</sub> were somewhat higher than predicted by
models. In addition HCl has been measured for the first time in
liquid aerosols. The chlorine isotope signature served as a unique
tool to identify unambiguously HCl dissolved in STS particles.
Within a narrow temperature range of about three degrees above the
frost point, the measured average amount of HCl in liquid particles
is below 1 weight%.