Comprehensive Study of Polar Stratospheric Clouds

Dr. Jochen Schreiner,

Jochen Schreiner, Max Planck Institute für Kernphysik, Heidelberg, Germany

A balloon-borne gondola for a comprehensive study of polar stratospheric clouds (PSCs) was launched on 25 January 2000 from Kiruna, Sweden. Besides a
mass spectrometer experiment for chemical particle analysis, the gondola carried optical particle counters, two backscatter sondes, a hygrometer and several
temperature and pressure sensors.

A mountain wave induced PSC was sampled between 20 and 23 km altitude. Strongly correlated data of PSC particle properties from the different instruments were obtained. A large variability of particle types was measured in several PSC layers, and particle development was followed for more than 2 hours. Liquid
ternary PSC layers were found at temperatures near the ice frost point. A large fraction of the sampled cloud layers consisted of solid nitric acid trihydrate (NAT) particles with a molar ratio H2O:HNO3 of 3 at temperatures near and slightly above the equilibrium temperature TNAT.

These observations, which are the first direct measurements indicating the existence of these solid hydrate particles in the atmosphere, will be presented and discussed.