DIRECTIONAL ANALYSIS OF EXTREME WIND SPEEDS IN POLAND

The paper deals with an analysis of extreme wind speeds for whole terr itory of Poland. Twenty-three meteorological stations having a complet e, or near-complete records from the period 1966-1990 were selected fr om 60 existing stations for the directional analysis of strong winds. The majority of these stations were chosen for their geographical loca tion and standard, open exposure. However, several stations with non-s tandard exposure were chosen to investigate the orographic effects on strong winds and exposure correction methods. The annual maxima of win d speeds from each of 12 sectors were abstracted from meteorological r ecords and the analysis was performed to give estimates of the Gumbel probability distribution. Ten-minutes mean values and gust speeds were analysed. In the first phase, the raw data were analysed without any correction for anemometer height, terrain roughness and topography. Ne xt the results will be corrected for each sector at each station. It h as been found that western winds dominate for majority of territory of Poland. Wind velocity pressure for sectors from northern through east ern to southern may be reduced to 50% of western values. Only in mount ains, where foehn winds occur, southern wind speeds are highest. Resul ts will be used to the zoning of the country in wind loads zones. Inte ntion is to harmonize these zones with all neighbouring countries.