Acta Scientiarum Polonorum

In the paper present state of the codification of soil freezing depth in Poland is presented as well as last
proposals of changes. Two of them are based on the use of so called air freezing index that is a method of
degreedays. New approach presented in the paper is based on the results of measurements of soil temperature
carried out by meteorological stations belonging to the Institute for Meteorology and Water Management
– State Research Institute. Annual (winter) maxima of the position of the zero centigrade temperature measured
in the soil were approximated by Gumbel probability distribution of extremes and characteristic values
of 50 year return period have been calculated. The soil structures at the meteorological stations were taken
into consideration and correction coefficients have been proposed. Proposal of a new map of soil freezing
depth in Poland is presented for the soil assumed as a reference one.