TENDENCIES OF CLIMATIC EXTREMES OCCURRENCE IN DIFFERENT MORAVIAN REGIONS AND LANDSCAPE TYPES

Abstract MUŽÍKOVÁ, B., VLČEK, V., STŘEDA, T.: Tendencies of climatic extremes occurrence in diff erent Moravian regions and landscape types. Acta univ. agric. et silvic. Mendel. Brun., 2011, LIX, No. 5, pp. 169-178 In this study present frequency of several characteristic days as tropical, summer, arctic, frost and ice days and also length of heat waves was compared with modelled future occurrence of these climate extreme indices. Climate-diagrams were used for drought hazard assessment. The main objective of our research was to detect possible changes of frequency of the extreme events toward future. Data from four localities in the Czech Republic (Moravia) were chosen for the evaluation. Each locality represents diff erent climatic, landscape and settlement conditions. Localities are represented by the closest grid points. Future trend was modelled for scenario data (scenario A1B) by regional model ALADIN-Climate/CZ in the Czech Hydrometeorological Institute. The results showed obvious rising tendency of tropical and summer days frequency on all localities, especially in lowland regions. Very strong decreasing trend seemed to be in occurrence of arctic days, which might be very scarce in the future. Frost days and ice days should also decrease. Increase in number of days in heat wave was considerable. Climate-diagrams showed possible rising drought hazard for all localities towards future periods. characteristic days, climatic extremes, ALADIN Extreme climatic events can have serious impact on environment and society. Analyses of observed temperature in many regions of the world have already shown some important changes in the extremes occurrence. The extreme climatic events are mainly associated with precipitation and temperature. Global air temperature has increased by an average of 0.74 °C (IPCC 4th Assessment Report 2007) in last hundred years. Generally, the global daily minimum and maximum air temperature values (Tmin and Tmax) increase, though the minima increase three times faster The research of tendencies of several climatic extreme indices has been realized in many countries all over the world. A study of the longterm changes of various climatic extremes was made jointly by a number of European countries. It was found that the changes in maximum and minimum temperatures follow the corresponding welldocumented mean temperature changes. Minimum temperatures, however, have increased slightly more than maximum temperatures, although both have increased. As a result, the study confi rmed that the diurnal temperature range has mostly decreased during the present century in Northern and Central Europe. Frost has become less frequent Not only changes in average or minimum and maximum air temperature are suitable to study changes of climatic conditions. Characteristic days (tropical, summer, ice, frost and arctic days) are also very useful indices. A research focused on such temperature characteristics was also done in Canada. Vincent and Mekis (2006) studied trends and variations in severa