Geographia Polonica (1997) vol. 70

Abstract

The effects of global warming on reference évapotranspiration are investigated and discussed in this report. There are numerous methods for estimating évapotranspiration in the literature. However, we chose to use two acceptable methods for an arid climate: the "Penman method" proposed by the Food and Agriculture Organisation of the United Nations (FAO), and the second one after Budyko-Zubenok, for the purpose of comparison.The amount of water needed for agriculture with and without climate change is estimated and discussed. A computer program based on Penman's method is used, with the necessary data, provided by a separate computer program. To compare results of different models, two climate scenarios were used in these analyses. The results show that the évapotranspiration will increase from north to south, due to an increase in temperature which is the result of the increase in the content of CO2, as well as of other greenhouse gases in the Earth's atmosphere.

Keywords: water scarcity, climate change, évapotranspiration, Libyan case study

Ali A. Almabruk, Institute of Geophysics, Polish Academy of Sciences ul. Księcia Janusza 64, 01-452 Warszawa, Poland

Abstract

Use was made of the longest-existing series of air temperature observations from Central Europe, specifically those for Warsaw, Kraków, Prague and Vienna. It was, above all, the course of mean annual values for air temperature that was analyzed, thus allowing this study to serve also as a basis for further, more precise studies including the variability and cyclicity of air temperature values in particular months. The application and attempted interpretation of periodograms drawn up on the basis of data for January, April, July and October has confirmed the above opinion. In general, considerable concurrence in the courses of mean air temperature values at the selected stations may be noted, and hence the influence of the same circulation mechanisms shaping air temperature over a large area during the two centuries.

Keywords: long air temperature series, mean annual air temperature, variability, periodicity

Janina Trepińska, Institute of Geography, Jagellonian University ul. Grodzka 64, 31-044 Kraków, Poland
Zbigniew Ustrnul, Institute of Meteorology and Water Management P. Borowego 14, 30-215 Kraków, Poland
Leszek Kowanetz, Institute of Geography, Jagellonian University ul. Grodzka 64, 31-044 Kraków, Poland

Abstract

The paper presents an analysis of thermal conditions in the Carpathian Foothills. Examples illustrating the influence of atmospheric circulation on the distribution and multi-year course of air temperature at sites located at the same parallel of latitude are given. This influence relates to the thermal conditions close to the Earth's surface in a given area and to the circulation processes occurring in the upper part of the troposphere. It has been observed that the effects of the circulation of a given type, represented by the index of the Atlantic progression (P), show up in the multi-year course of temperature and differ in character in particular seasons of the year.

Keywords: atmospheric circulation, circulation indices, climatic variability, mean maximum, mean minimum

Danuta Limanówka, Institute of Meteorology and Water Management ul. Piotra Borowego 14, 30-215 Kraków, Poland

Abstract

The paper presents an analysis of recent trends for precipitation in the Carpathians on the basis of data for the period 1951-1995. Temporal variability in precipitation was examined based on area-averaged data for the Carpathians and then separately for the eastern and western parts. Overall precipitation totals in the Carpathians show downward trends, which are visible in summer and winter but which contrast with opposite trends in spring and summer. The largest declines in precipitation totals are observed in summer, a phenomenon especially well-pronounced in the western part of the Carpathians, while smaller declines have occured in winter, mainly in the eastern part of the Carpathians. Spring and autumn precipitation in the Carpathians is increasing, but there is agreement between the trend and the course of precipitation in the whole Carpathians. Agreement between the course and trend in precipitation and the cyclonicity index (C) is also observed.

Keywords: Carpathians, areal precipitation, trend, cyclonicity index

Elżbieta Cebulak, Institute of Meteorology and Water Management ul. Piotra Borowego 14, 30-215 Kraków, Poland

Abstract

The paper analyses long-term variability in the number of days with precipitation in Kraków in relation to changes in atmospheric circulation. Data on annual, semi-annual and seasonal numbers of days with precipitation > 0.1 mm in the 1814-1995 period and data on days with precipitation >1.0 mm and > 10.0mm for the years 1850-1995 were used. For precipitation threshold values, averages, maxima, minima, standard devia-tions and variability coefficients are presented. For the 1874—1995 series, correlation coefficients between the number of days with precipitation and the index of cyclonicity - C, determined on the basis of the classification of circulation types proposed by T. Niedźwiedź, are calculated. It was found that the number of days with precipitation >0.1 mm and > 1.0 mm shows significant positive trends in the cold half of the year and in the winter period, and negative trends in the warm half of the year and in the summer period. The variation in the number of days with precipitation >0.1 mm and >1.0 mm shows significant correlation with fluctuations of the C index which is most pronounced in the cold half of the year.

Keywords: variability, trends, number of days with precipitation, atmospheric circulation, Kraków

Robert Twardosz [r.twardosz@uj.edu.pl], Department of Climatology, Institute of Geography of the Jagellonian University ul. Grodzka 64, 31-044 Kraków, Poland

Abstract

The paper attempts an evaluation of winter thermal differentiation in the Carpathian altitudinal profile in relation to some external and internal factors of the montane climatic system. Mean monthly, mean daily and daily maximum air temperatures were taken, for three stations representing different altitudinal climatic zones, in the period 1961/62-1990/91. The variability of the dates of winter commencement and end, winter duration and thermal indices were analysed, as was the relation between the occurrence of frosty days and atmospheric circulation characteristics. The biggest decrease in the examined period was observed for the numbers of winter days and frosty days in Zakopane and Krakow, while at Kasprowy Wierch mountain the number of winter days increased slightly and the number of frosty days decreased. It was established that winter thermal conditions at Kasprowy Wierch depend above all on air circulation and advection conditions in the free atmosphere, while at the two other stations, located in urban areas, anthropogenic factors interfere with natural climate changes

Keywords: winter, air temperature, Carpathian Mountains, climatic vertical zones

Katarzyna Piotrowicz [k.piotrowicz@iphils.uj.edu.pl], Institute of Geography and Spatial Management, Jagiellonian University Grodzka 64, 31-044 Kraków, Poland

Abstract

Variability is one of the characteristic features of polar geoecosystems. On the meso- and macro-time scales, the variability of geoecosystems can be expressed in relation to: irregular interannual changes, multi-year cyclic changes, year-to-year directional changes and anthropogenic changes. Polish multidisciplinary research concerning the physical, chemical and biological processes in the region of Admiralty Bay (King George Island, South Shetland Islands) demonstrates such variability.

Keywords: variability, geoecosystem, South Shetland Islands, climate change

Stanisław Rakusa-Suszczewski, Department of Antarctic Biology, Polish Academy of Sciences ul. Ustrzycka 10, 02-141 Warszawa, Poland
Anna Kidawa, Department of Antarctic Biology, Polish Academy of Sciences ul. Ustrzycka 10, 02-141 Warszawa, Poland