Influence of NAO on forming the UTCI index in Kłodzko

The aim of this paper is to understand the role of the macrocirculation factor in shaping the dynamics of long-term bioclimatic conditions, with reference to Klodzko in the Polish part of the Central Sudetes. The variability of bioclimatic conditions in Klodzko for the period 1966–2017 was analysed, exposing its local specificity. The Universal Thermal Climate Index (UTCI) was taken as an indicator of the analysed bioclimatic features. The influence of the North Atlantic Oscillation (NAO) on the variability of this index and its constituent meteorological elements, e.g. air temperature, vapour pressure, wind speed, and solar conditions, was examined. On the basis of the winter NAO Hurrell coefficient, the analysed years were divided into two opposing groups representing either a negative or positive Hurrell index. A comparison between these two year-groups for the mean values of UTCI and the examined meteorological elements showed a clear intergroup difference in these values. Except for cloudiness, the importance of the macrocirculation genesis of NAO was verified by the statistically significant correlation between the Hurrell index on the one hand and the tested UTCI index and its constituent meteorological elements on the other.