High atmospheric pressure and accompanying cold season weather types in Poland (1951-2010)

ABSTRACT: Recent climate change manifests itself in changes to the properties and frequency of particular weather types. This study explores the statistical characteristics of weather types that accompanied strong high sea level pressure (≥1030 hPa ‘SHP’) over Poland during the period from 1951 to 2010. Sea level pressure NCEP/NCAR Reanalyses data of 2.5° × 2.5° resolution, as well as observed climatic data from 8 Polish weather stations are used. There was a small increase in SHP frequency during the study period in the cold half-year (October to March), especially for synchronous SHP occurring over the entire territory of Poland. The dominant weather types accompanying SHPs were ground frost and frosty types, although cool and moderately warm types were also frequent. In most cases, days with SHPs were without sunshine and without precipitation. The long-term variability in the frequency of occurrence of particular weather types on days with SHP indicates an increase in the frequency of warmer weather after 1980 as compared to the period before that year. However, this warming demonstrates significant regional and seasonal variation.