The paper analyzes the air temperature characteristics in Bosnia and Herzegovina in order to identify recent trends in mean air temperature. Trends in annual, seasonal and monthly mean air temperatures during 1961-2015 periods were determined based on data from sixteen meteorological stations. MAKESENS procedure (Salmi, et al., 2002), which uses the nonparametric Mann-Kendall test and the nonparametric Sen's method, was applied on time series of annual, seasonal and monthly mean air temperatures to assess the trend magnitude and its statistical significance. Given the results, the warming trend is present all over Bosnia and Herzegovina. Significant positive trends in annual and summer temperatures were detected over the entire territory (p<0.01). Positive winter and spring trends are largely significant (p<0.01 or p<0.05), whereas autumn trends are low and insignificant. The highest increase was registered in June-August and December-January periods. In some areas, a low negative trend was present in September and November. A significant positive correlation between East-Atlantic pattern index and temperature was determined over the entire territory of Bosnia and Herzegovina throughout the year. Winter and spring temperatures were also significantly related to the North Atlantic Oscillation index and Arctic Oscillation index, respectively.

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Аbstract⎯Changes in extreme precipitation indices over the Peripannonian region of Bosnia and Herzegovina were examined. Data on daily precipitation during the period 1961-2016 from four meteorological stations were used for the calculation of 13 indices recommended by the Expert Team on Climate Change Detection and Indices (ETCCDI) for the climate change assessment. The precipitation change assessment covered trend analysis and analysis of changes in distribution. Determined patterns of change were neither spatially nor temporally coherent. The estimated trends in extreme precipitation indices were mixed in sign and mostly insignificant. Moreover, no significant changes in distribution of majority indices were determined. However, the upward trends in heavy precipitation indices RX1day, RX5day, R95p, and R99p indicate changes towards more intense precipitation. Understanding patterns of precipitation changes is of a great pertinence in many applied studies: flood risks management, agricultural planning, water resources management, environment conservation, etc.

The paper analyzes trends in the extreme temperature indices based on fixed thresholds in Bosnia and Herzegovina during the 1961-2016. Based on data from 12 meteorological stations, trends in both warm and cold temperature indices were determined using the nonparametric Mann-Kendall test and the nonparametric Sen's slope estimator. The observed tendencies in indices based on fixed thresholds were as expected in a warming world -warm temperature indices (summer days, tropical days and tropical nights) displayed the significant positive trends, whereas cold temperature indices (icing days and frost days) showed the downward tendencies. The annual occurrence of summer days and tropical days increased on average for 5.3 and 4.8 days per decade, respectively, whereas icing days and frost days displayed downward trends in the range of -1.7 and -3.6 days per decade, respectively. The obtained results indicate that the climate system warming was more a result of very pronounced positive trends in the warm temperature indices than the downward tendency of cold ones. The most prominent changes were observed in Banja Luka, Bugojno and Zenica regions. Both trends, positive in warm indices and negative in cold ones, become more pronounced in the 1990s and particularly since the beginning of the 21 st century. Further research should focus on the assessment of the observed trends impacts on natural and socio-economic systems.

Changes in annual and seasonal precipitation over the East Herzegovina region in Bosnia and Herzegovina during the 1961-2016 periods were analyzed based on data sets of daily precipitation from 14 meteorological stations and rainfall gauges. The results show a downward trend in annual precipitation over the entire East Herzegovina region. Seasonal trend analysis showed that negative trends prevailed throughout the year, except in autumn season. Most prominent negative trends were registered in summer season throughout the region. In winter and spring season, precipitation displayed trends of both sign (although a downward trend prevailed). In the autumn season, precipitation has increased almost throughout the entire East Herzegovina region. However, a majority of estimated trends in annual and seasonal precipitation were weak and statistically insignificant. Prevailing negative values of the Rainfall Anomaly Index since the 1990s also suggest that precipitation reduction was present over the East Herzegovina region. Analysis of the Cumulative Precipitation Anomalies showed that a dry period started in 1981 and still continues. Precipitation variability was strongly dictated by the large-scale atmospheric circulation patterns over the Northern Hemisphere, such as the North Atlantic Oscillation, the East Atlantic/West Russia pattern and the Arctic Oscillation, particularly during winter season.