1. 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

2. 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

3. 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

4. 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

5. weather types
to find a possible explanation of such behaviour, an analysis of the upper atmosphere circulation was done for period
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 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

6. 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

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

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

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

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

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

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

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

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

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

16. 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

17. 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

18. 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

19. 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

20. 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,
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, ;
12th EMS Annual Meeting & 9th European Conference on Applied Climatology, Łódź, Poland

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