Annual and seasonal extreme precipitation events in Novi Sad

Serbia is located in the central part of the Balkan Peninsula, and is characterized by a continental climate in the north, a temperate continental climate in the central part and a modified Mediterranean climate in the south. The average annual precipitation is between 500 and 700 mm in the lowlands and over 1000 mm in the mountains. Novi Sad (45°20’ north latitude, 19°51’ east longitude, 84 m altitude) is located in the south of the Pannonian Plain and is the capital of the autonomous province of Vojvodina in northern Serbia. The average annual precipitation in the period 1961-2020 amounted to 655.5 mm.The following extreme precipitation events were analysed based on daily precipitation data from 1961 to 2020 in Novi Sad: very heavy precipitation days (RR20), highest 1-day precipitation amount (Rx1d) and highest 3-day precipitation amount (Rx3d). The modified Mann-Kendall test (MMK) and the Sen’s slope method are used to examine the possible trends and their magnitudes. The generalised extreme value distribution (GEV) and the generalised Pareto distribution (GPD) were used for the analysis of extreme precipitation.A small number of RR20 was observed in all seasons except summer. The lowest number of heavy precipitation days was recorded in winter. The mean value of RR20 was 2.4 from 1961 to 1990 and 3.2 from 1991 to 2020 in summer, with a maximum value of 9 and 8, respectively. The highest 1-day and 3-day precipitation values were measured in summer. The highest values of Rx1d (121.9 mm) and Rx3d (149.4 mm) were observed in spring 2015. A significant positive trend was observed for Rx3d in all seasons, for Rx1d in spring, summer and fall and for RR20 in spring and fall. A positive but non-significant trend was observed for Rx1d in winter and for RR20 in summer. A significant positive trend was observed for all indices on an annual basis.The GPD distribution was fitted to the daily precipitation series with a threshold of 20 mm in Novi Sad. The maximum likelihood estimates of the location and scale parameters were 30.36 and 197.7, respectively. Maximising the GEV log-likelihood for Rx1d and Rx3d leads to the estimation of the shape parameter 0.31 for Rx1d and 0.17 for Rx3d, respectively. The positive values of the shape parameter indicate that the Fréchet distribution was fitted to the highest 1-day and 3-day precipitation amounts in Novi Sad.