Formation of solid particles in synoptic-scale Arctic PSCs in early winter 2002/2003 N. Larsen1, B. M. Knudsen1, S. H. Svendsen1, T. Deshler2, J. M. Rosen2, R. Kivi3, C. Weisser4, J. Schreiner4, K. Mauerberger4, F. Cairo5, J. Ovarlez6, H. Oelhaf7, and R. Spang8 1Danish Meteorological Institute, Lyngbyvej 100, DK-2100 Copenhagen, Denmark 2University of Wyoming, Laramie, WY 82071, USA 3Finnish Meteorological Institute, Arctic Research Centre, 99600 Sodankyla, Finland 4Max-Planck-Institut für Kernphysik, Bereich Atmosphärenphysik, Postfach 103 980, 69029 Heidelberg, Germany 5Istituto di Scienze dell’Atmosfera e del Clima, via Fosso del Cavaliere 100, 00133 Roma, CNR, Italy 6Laboratoire de Météorologie Dynamique, CNRS-IPSL, Ecole Polytechnique, 91128 Palaiseau cedex, France 7Forschungzentrum Karlsruhe, Institut für Meteorologie und Klimaforschung, Postfach 3640, 76021 Karlsruhe, Germany 8Forschungzentrum Jülich, Institute for Chemistry and Dynamics of the Geosphere, Institute I: Stratosphere (ICG-I), 52425 Jülich, Germany
Abstract. Polar stratospheric clouds (PSC) have been observed in early winter
(December 2002) during the SOLVE II/Vintersol campaign, both from balloons
carrying comprehensive instrumentation for measurements of chemical
composition, size distributions, and optical properties of the particles, as
well as from individual backscatter soundings from Esrange and
Sodankylä. The observations are unique in the sense that the PSC
particles seem to have formed in the early winter under synoptic temperature
conditions and not being influenced by mountain lee waves. A sequence of
measurements during a 5-days period shows a gradual change between liquid
and solid type PSCs with the development of a well-known sandwich structure.
It appears that all PSC observations show the presence of a background
population of solid particles, occasionally mixed in with more optically
dominating liquid particles. The measurements have been compared with results from a
detailed microphysical and optical simulation of the formation processes.
Calculated extinctions are in good agreement with SAGE-III
measurements from the same period. Apparently the solid particles are
controlled by the synoptic temperature history while the presence of liquid
particles is controlled by the local temperatures at the time of
observation. The temperature histories indicate that the solid particles are
nucleated above the ice frost point, and a surface freezing mechanism for
this is included in the model. Reducing the calculated freezing rates by a
factor 10-20, the model is able to simulate the observed particle size
distributions and reproduce observed HNO3 gas phase concentrations.
Citation: Larsen, N., Knudsen, B. M., Svendsen, S. H., Deshler, T., Rosen, J. M., Kivi, R., Weisser, C., Schreiner, J., Mauerberger, K., Cairo, F., Ovarlez, J., Oelhaf, H., and Spang, R.: Formation of solid particles in synoptic-scale Arctic PSCs in early winter 2002/2003, Atmos. Chem. Phys., 4, 2001-2013, doi:10.5194/acp-4-2001-2004, 2004.