11th Conference on Atmospheric Radiation and the 11th Conference on Cloud Physics

Monday, 3 June 2002
Influence of Embedded Convection on Microphysics of Precipitation (Formerly Paper 8.3)
Björn R. Baschek, ETH Zürich, Zürich, Switzerland; and R. Schefold, M. Wüest, and E. Barthazy
Poster PDF (891.5 kB)
The connection between embedded convection and riming is generally acknowledged. However, experimental observations of the riming degree of ice crystals together with convective parameters are scarce and several questions cannot be answered satisfactorily:

Which dynamic or thermodynamic reasons are causing embedded convection? What are the correlations to the microphysics of riming? The answers to these questions are of fundamental interest to understand the formation of precipitation and thus also of interest for ,e.g., high resolution weather modelling.

To answer some of the open questions, a field experiment is in progress in the pre-alpine region of Switzerland. At the base of a mountain a vertically pointing X-band Doppler radar with 1s temporal and 50m spatial resolution is situated below the melting layer measuring the full Doppler spectrum of the precipitation particles. On the top of the mountain, above the radar, ice precipitation is observed with an optical disdrometer, measuring the size distribution of the ice particles. In addition, ice crystals are replicated (Formvar) to determine their size, habbit and riming degree.

The horizontal windfield around the experimental site is monitored with two C-band Doppler radars, working in dual Doppler mode. These windfields are used to identify possible reasons for the generation of the embedded convection.

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