Badania Fizjograficzne, Seria A, Tom 64, 2013
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Item Charakterystyka zlodzenia jezior Wielkopolskiego Parku Narodowego i jego otuliny(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2013) Choiński, Adam; Ławniczak, Agnieszka; Ptak, MariuszThis study presents the characteristics of ice phenomena occurring on selected lakes in the Wielkopolski National Park based on long-term observations of Góreckie Lake (1971–1992) and fieldwork performed in February 2012 on six other water bodies. The investigation revealed the advancement of ice phenomena appearance within the space of twenty years, as well as the advancement of their disappearance. Such a situation also concerned the ice cover. In turn, the analysis of maximum ice thickness showed an incre- asing trend, while the number of days with compact ice cover decreased. No direct relationship was observed between the rise in average annual water temperature and the delay in the appearance of ice phenomena in a subsequent year. Variation in ice cover thickness measured on the six lakes studied in February 2012 was low and amounted to only 5.5 cm. The thickest (35 cm) and the thinnest (29.5 cm) ice was recorded on the same water body. Fieldwork showed that ice cover thickness was mostly determined by climatic conditions and not influenced by the individual features of the consecutive lakes.Item Zróżnicowanie grubości pokryw lodowych wybranych jezior Wielkopolski(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2013) Choiński, Adam; Ptak, MariuszIn this study the thickness of ice cover on six lakes in Wielkopolska was measured. Lakes were selected so that they were located on a north-south axis and the distance between the furthermost water bodies amounted to 105 km. The remaining features of the lakes were random. The investigation revealed that the va- riability in ice cover thickness was rather low, not exceeding 4 cm. In the case of Kórnickie Lake, the number of measurements performed was higher (20 boreholes; 2 boreholes in the remaining lakes) in order to assess the variation in ice cover thickness within one lake. Those analyses revealed that the difference amounted to only 2 cm. The thinnest ice cover was observed in the inflow and outflow areas of the Głuszynka river. Analysis of the relationship between ice cover thickness and latitude showed that it increased to the south. That thesis, however, must be verified by more detailed research which would include more lakes, their individual features and synchronized time series of at least several years.Item Wpływ cyrkulacji atmosferycznej na występowanie ekstremalnych opadów w Poznaniu w latach 1920-2010(Wydawnictwo Poznańskiego Towarzystwa Przyjaciół Nauk, 2013) Bernas, Marcin; Kolendowicz, LeszekThe aim of this work is to define the influence of atmospheric circulation on the occurrence of extreme precipitation in Poznań in the years 1920–2010. The daily totals for atmospheric precipitation taken at the IMGW Poznań Ławica meteorological station were used. The research also uses data collected from the NCEP/NCAR Reanalysis (Kalnay et al. 1996) concerning the distribution of atmospheric pressure at sea level, the geopotential height of 500 hPa as well as an indicator for the availability of precipitable water (PW). Data on the frequency of occurrence of Grosswetterlagen atmospheric circulation from 1920–2000 was also used.