Analysis of atmospheric circulation changes over the Adriatic coast in warm period 1981-2010. Marija Mokorić and Lovro Kalin Meteorological and Hydrological Service of Croatia 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

outline introduction analysis conclusions and future work Croatia: summer months climate conditions recent changes analysis weather types (upper atmosphere) conclusions and future work 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

introduction In the last decade it was observed that the period of relative dry weather has been extended to July, and to the end of August and September more frequent months with less precipitation and higher air temperature, compared to climatological average longer firefighting season 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

introduction a large number of fires appeared in period 2001-2010 not only on the coast, but for the first time in the mountain region since 2005 the most dangerous fires appeared at the end of August and first part of September, when the extreme fires are not so common 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

weather types to find a possible explanation of such behaviour, an analysis of the upper atmosphere circulation was done for period 1981-2010 fires are connected with weather types and atmospheric circulation mean monthly circulation AT 500 hPa (~5.5 km) on the Northern hemisphere (Deutsche Wetterdienst) period 1981-2010 for June, July, August and September the weather pattern typing is done manually 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

weather types DRY WET eight main atmospheric circulation patterns Bischoff and Vargas (2003): upper cyclone CY upper through TR front side of upper through (south-west str.) SW west-stream W back side of upper through (north-west str.) NW upper atmospheric ridge R non-gradient field NG front side of the ridge FR DRY WET 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

back side of the trough (NW stream) source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

source: Deutscher Wetterdienst front side of the ridge source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

source: Deutscher Wetterdienst upper ridge source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

source: Deutscher Wetterdienst non-gradient field source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

source: Deutscher Wetterdienst west stream source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

front side of the trough (SW stream) source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

source: Deutscher Wetterdienst upper trough source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

source: Deutscher Wetterdienst upper cyclone source: Deutscher Wetterdienst 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

summer - autumn at the beggining of autumn, weather conditions change 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

in 2000’s occurence of ‘dry’ weather types (NG, NW) has increased June... 80’s TR NW W SW 90’s NG R 00’s FR in 2000’s occurence of ‘dry’ weather types (NG, NW) has increased 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

since 2005, occurence of ‘dry’ weather types (NG, NW) has increased September... 80’s W NG NW SW R TR 90’s 00’s since 2005, occurence of ‘dry’ weather types (NG, NW) has increased 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

conclusions in July and August no significant change is observed since 2005, in June and September occurence of ‘dry’ weather types (NG, R) has increased hot and dry season has expanded matches well with fire-fighter’s experience 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

future work go into more detailed analysis spatial (northern and southern Adriatic) temporal (order of weeks, days...) 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

references Bischoff S. A. and Vargas W. M. (2003): The 500 and 1000 hPa weather type circulations and their relationship with some extreme climatic conditions over southern South America. Internationa Journal of Climatology, 23, 541-556 Lončar, E. and Bajić, A. (1993): Weather types in Croatia (in Croatian). Croatian Meteorological Journal, 29, 31-45 Mokorić, M (1998): The Weather Types on Adriatic Coast of Croatia during the Season of Forest Fire Protection, Proceedings of III International Conference on Forest Fire Research, Coimbra-Luso, 1, 1305-1309; 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

Thank you for your attention! 12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland