engleski

Numerical modeling of meteorological conditions during the 2015 wildfires on Pelješac Peninsula

Weather situation during the two forest fires, which were intentionally caused on the Pelješac Peninsula on the night 20/21 July, has been analyzed. The aim of this study is to research weather conditions that led, with the help of human factor to the begging of fire and to validate numerical simulations of models WRF and ALADIN/HR during the first few days of fire. The lack of precipitation and extremely hot weather in July caused the worst possible forest fires - fire crown. During the wildfires slightly lower air pressure prevailed on the southern Adriatic, and the warm air was up to 850 hPa. At the beginning of wildfires air temperature at 2 m achieved 39°C and relative humidity was around 40% during the day. Few hours before fires wind gusts reached 12 m/s. Canadian forest fire weather index (FWI) showed high risk of wildfire until 26 July 2015. Haines index showed high risk of forest fire during the day and moderate risk during nights. Simulated air temperature for both models gave good results, but model WRF produced slightly lower maximum temperature than observed temperature. However, some meteorological elements of the WRF and ALADIN models predicted differently. ALADIN/HR model produced lower relative air humidity, and WRF higher than observations, due to different model setup and selected parameterization. While model ALADIN/HR significantly underestimates 10-minutes mean wind speed, WRF overestimates them. We also compared simulated fields developed by the ALADIN/HR and WRF models with upper air observations. WRF model usually predicts higher wind speed up to 1 km altitude. But it should be noted that weak wind up to 5 m/s prevailed in the troposphere lower layer during the fire except at night on the beginning of fire the WRF model simulated a maximum of 12 m/s. Both models predicted decreasing air temperatures with height and almost neutral stratification of atmosphere. Although the man intentionally set fire, meteorological observations indicate very favorable weather conditions (dry and hot weather) in Pelješac Peninsula in the days before and during fires, for the outbreak and rapid spread of wildfire. Such weather conditions and very steep and inaccessible terrain have hampered fire-fighting which endangered human lives and residential buildings.

wildfires, Adriatic, WRF-ARW, ALADIN/HR, FWI, Haines index

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