Icing Frequency

The map shows the frequency of meteorological icing at 100 m height above ground for the period between August 2007 and July 2009. The 10-year-average value of icing frequency is about 5% lower.

The map is based on raster information on cloud water, temperature and wind from the analysis of COSMO-2, the weather forecast model of MeteoSwiss. This data is used as input for an icing algorithm that simulates the ice mass accretion on a freely rotating cylindric structure. The simulated icing frequency is given on a 2.2 km raster and was verified using measurements from the IMIS measurement network in the Alpine region and measurements in the Jura region.

Icing influences the planning of a wind energy project as well as the operation of wind turbines (WT) in several ways:

What does "meteorological icing" mean?

Icing of meteorological instruments as well as other structures proceeds in different stages that may be described as follows:


Figure: Different stages during the icing of meteorological instruments or other structures.

The period of instrumental icing is generally much longer than that of meteorological icing.

Interpretation of the map

The map of icing frequency allows to qualitatively evaluate the risk of icing and to judge if it is necessary to make further arrangements during the planning phase of a wind energy project. When using the map the following issues should be considered:

Further information

A detailed description of the methodology and the verification results is given in the final report of the research project "Vereisungskarte der Schweiz" (supported by the SFOE).

Further information about icing: