Frequency Analysis of Extreme Temperature Events

Two main meteorological stations from two different climate regions of Croatia (the continental and the coastal region) have been selected to analyse the annual number of days above 90th percentile (days fall under the categories considerably warm and extremely warm) and days below 10th percentile (days within the categories considerably cold and extremely cold). In other words, all available daily mean temperatures for Zagreb-Grič and Split-Marjan are compared with the multi-annual average (1961-1990), which is common practice in climate analyses. Moreover, temperature anomaly for each day is expressed as a percentile. Secular trends at the Zagreb-Grič Observatory (18622012) of the annual number of days above 90th percentile indicate a positive significant trend of 19.0 days/100 years whilst for days below 10th percentile, a significant negative trend of -18.1 days/100 years could be observed. At Split-Marjan (1948-2012) trends were not significant in both cases. There was the positive significant trend of 0.5 days/10 years for days above 90th percentile and negative non significant trend of -1.0 days/10 years for days below 10th percentile. The significance of linear trends was tested by Mann-Kendall test for a 0.05 significance level. The results obtained show that extreme temperature trends follow global warming trends in continental part of Croatia, represented by Zagreb-Grič, whilst it is not the case in the coastal region, represented by Split-Marjan.