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WEATHER ANALYSIS OF EXTREME FOREST FIRE ON ISLAND BRAČ FROM 14

TO 17 JULY 2011

Boris Mifka

Višnja VučetićMeteorological and Hydrological Service

Maja Telišman PrtenjakGeophysical Departement "Andrija Mohorovičić" of the

Faculty of Science, University of Zagreb

Bihać, 28 April 2014

Photo: Siniša Miličić 14.7.2011 14:57

• WILDLAND FIRE POTENTIAL DANGER IN LONG LASTING DRY AND HOT PERIODS

• EXTREME FOREST FIRE BEHAVIORHIGH SPEED OF FIRE SPREAD, OCCURENCE OF MULTIPLE FIRE FRONTS

• OBJECTIVE TO ANALYZE WEATHER CONDITIONS DURING WILDLAND FIRE AT THE ISLAND BRAČ FROM 14 TO 17 JULY 2011

TO EXPLAIN DYNAMIC ATMOSPHERIC PROCESSES WHICH INFLUENCED EXTREME WILDLAND FIRE BEHAVIOUR

• AREA LOST IN FIRE WAS ABOUT 5600 ha (average annual burnt area is about 9000 ha )

INTRODUCTION

Island of BračIsland of Brač 14 July 201114 July 2011..

Source: Vuko, 2011

(Photo by:Siniša Miličić http://https://plus.google.com/110700915204596022370/posts/85atoEBhe5K (Photos by:Predrag Mandić i Pero Dragičević, http://www.braconline.com.hr)

Split-Marjan

Zadar-airport

Hvar JelsaBol

SutivanBol-airport

Synoptic and automatic stationsClimatological stationsRadio-sounding stationAutomatic station

Zagreb

DATA

METEOROLOGICAL ELEMENTS:WIND SPEED AND DIRECTION,RELATIVE HUMIDITY, AIR TEMPERATURE AND PRESSUREMETEOROLOGICAL STATIONS AND DATA:10-min DATA FROM AUTOMATIC STATIONS HOURLY DATA FROM SYNOPTIC STATIONSDATA AT 7,14 I 21 H CET FROM CLIMATOLOGICAL STATIONS RADIO-SOUNDING DATA AND VERTICAL PROFILES

PrecipitationRelative humidityWind speedAir temperature

PrecipitationRelative humidityAir temperature

PrecipitationAir temperature

FFMC DMC DC

Wind speed ISI BUI

FWI

CANADIAN FWI METHOD

RESULTS FWI METHOD

• MID-ADRIATIC, JUNE AND JULY 2011 DRY AND HOT WEATHER

1 21 42 63 84 105 126 147 168 189 210 231 252 2730

20

40

60

80

100

120SPLIT-MARJAN, 1.1-30.9.2011.

dani

FF

MC

,IS

I,F

WI

FFMC ISI FWI

SYNOPTIC SITUATION

TFP ADVECTION

14 July 2011

DIURNAL CYCLES OF WIND SPEED AND DIRECTION

wind speed (m

/s)w

ind speed (m/s)

win

d di

rect

ion

( °)

win

d di

rect

ion

( °)

FIRE STARTFIRE START


CETCET

CETCET

Datum

Tmaks (°C)

Tmin (°C)

Tsred (°C)

RVsred (%)

RV14 (%)

14.7.2011. 35.0 27.0 31.5 35 38 15.7. 2011. 32.0 25.2 27.6 61 58 16.7. 2011. 31.8 22.7 27.8 59 50 B

OL

17.7. 2011. 30.6 22.2 26.4 40 42 14.7. 2011. 36.2 25.2 30.6 64 59 15.7. 2011. 34.1 20.2 29.1 60 63 16.7.2011. 35.0 19.7 29.6 55 57

SU

TIV

AN

17.7.2011. 32.5 19.7 28.8 57 55

AIR TEMPERATURE AND REL. HUMIDITY

AIR PRESSURE

DIURNAL CYCLES



air

te

mp

era

ture

( °

C)

a

ir t

em

pe

ratu

re (

°C

)

CETCET

CETCET

r

ela

tive

hu

mid

ity (

%)

r

ela

tive

hu

mid

ity (

%)

air

pre

ssu

re (

hP

a)

air

pre

ssu

re (

hP

a)

DATEDATE

SURFACE METEOROLOGICAL FIELDS SIMULATIONS OF ALADIN/HR MODEL

14. 7.2011. – WEAK ANTICYCLONE ON MESOSCALE (MA) OVER BOSNIA, SHALLOW CYCLONE OVER ADRIATIC SEA ( 1010 hPa ISOBARE IS OVER BRAČ AND HVAR)

• Vmaks 8–10.8 m/s NEAR BRAČ

BOTTOM SIDE OF MA : SE SE–E WIND INCOMING DRY AND HOT AIR FROM THE DALMATIAN HINTERLAND (RH < 40 % & Tmaks = 35 °C)

14.7.2011. WIND

RELATIVE HUMIDITY AIR PRESSURE

0 2 4 6 8 10 12 14 16 180.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0ZADAR-A SONDAŽA 14-17.7.2011.

brzina vjetra (m/s)

vis

ina (

km

)

14.7. 00 UTC

14.7. 12 UTC

15.7. 00 UTC

15.7. 12 UTC

16.7. 00 UTC

16.7. 12 UTC

17.7. 00 UTC

17.7. 12 UTC

0 90 180 270 3600.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

smjer vjetra ( °)

vis

ina (

km

)

ZADAR-AIRPORT 14–17 July 2011.00 and 12 UTC

-INVERSION TOP 994 m

-LOW LEVEL JET 12. 9 m/s at 379 m

-INVERSION TOP 994 m

-LOW LEVEL JET 12. 9 m/s at 379 m

0 2 4 6 8 10 12 14 16 180.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0vis

ina (

km

)

brzina vjetra (m/s)

BOL 14 .7.2011 ALADIN/HR

8 UTC

9 UTC

10 UTC

11 UTC

12 UTC

13 UTC

14 UTC

15 UTC

0 90 180 270 3600.0

0.5

1.0

1.5

2.0

2.5

3.0

3.5

4.0

smjer vjetra ( °)

BOL ALADIN:14 July 2011. 8-15 UTC

WIND SPEED MAX <12m/sWIND SPEED MAX <12m/s

(source: http://satreponline.org)

VERTICAL CROSSECTIONS, 14 July 2011 at 12 UTC

WARM ADVECTION BUOYANCY SPEED

• LOADED GUN THEROY – TEMPERATURE INVERSION AS A CAP ON A STEAM POT

• CIN = -417.83 J/kg AT ZADAR-A & CAPE 463.01 J/kg

• MECHANISM OF CONVECTION TRIGGERING – VISINSKA CIKLONA CUT OFF, WITH CONVECTIVE CLOUDINESS AT WATER WAPOR SATELITE IMAGES

THOUGH IT WAS TO DRY FOR CONVECTIVE CLOUDINESS

DEVELOPEMENT

• VCS INCREASED VERTICAL SPEED VERTICAL SPEED (-2 DO -4 hPa/h 0.5–1 cm/s od 950–700 hPa) 14 to15 July 2011 Max. at 700 hPa

WARM ADVECTION TEMPERATURE INVERSION?

CONCLUSION

• GREAT AREA AFFECTED BY FIRE (ROUND 5200 ha)

• DRY AND HOT CONDITIONS BEFORE THE FIRE START HIGH FWI INDEX

• MODERATE TO STRONG SE WIND PRECEDED THE FIRE START

• MESOSCALE: SHALOW CYCLONE ABOVE ADRIATIC SEA AND WEAK ANTIYCYCLONE OVER BOSNIA DURING THE PASAGE OF DRY FRONT

• SOUNDINGS STABILE LAYER AT 994 m, LOW LEVEL JET BELOW, INCOMING COLD FRONT EXTREME WILDLAND FIRE BEHAVIOUR

• IMPACT OF THE WARM ADVECTION ON STABILE LAYER – DISTORTION (LOADED GUN THERY) ?

• IN THE MORNING OF 15 July 2011, WEATHER CHANGE ETESIA WINDS+SEA BREZE MAESTRAL

THANK YOU !

ALADIN/HR• HYDROSTATIC MODEL WITH 8 KM HORIZONTAL RESOLUTION AND 37

VERTICAL LEVELS (LOWEST AT 17 M)

• SPECTRAL MODEL WITH TERAIN FOLOWING VERTICAL COORDINATE

• PRIMITIVE EQUATION SYSTEM AND PHYSICAL PARAMETRIZATION INCLUDED

OPERATIVE MODE INITIAL AND BOUNDARY CONDITIONS (APPROVED BY RCLACE DATA ASSIMILATION CYCLE - ARPEGE (Meteo France) )

DYNAMICAL ADAPTATION downscaling from 8 km to 2 km resolution on a 450 X 450 point grid

PRILOG 1

14.7.2011 U 12 UTC USPOREDBA

RADIOSONDAŽNIH MJERENJA I PROCJENE

MODELA ALADIN/HR

14.7.2011 U 12 UTC USPOREDBA

RADIOSONDAŽNIH MJERENJA I PROCJENE

MODELA ALADIN/HR

PRILOG 2

Prognostički vertikalni vremenski presjek atmosfere za Bol od 14. do 16. srpnja 2011. prema modelu ALADIN/HR.

PRILOG 3

PRILOG 4

VERTIKLANA STRUKTURA ATMOSFERE I USPOREDBA S NUMERIČKIM SIMULACIJAMA

• U POČETKU ŠUMSKOG POŽARA OKO 2000 ha IZGORENOG RASLINJA U VREMENU OD 2 SATA NAKON POČETKA, UZ POPRATNE ZANIMLJIVE METEOROLOŠKE POJAVE

• MET- VELIČINE IZ RADIOSOANDAŽE I PSEUDOTEMPOVI (ALADIN/HR): BRZINA I SMJER VJETRA, TEMPERATURA I POT. TEMPERATURA ZRAKA I UZGONSKA FREKVENCIJA

SONDAZA:• VJETAR : 14.7.2011. U 12 UTC MAKS. BRZINA OD 12.9 m/s NA

379 m MLAZNA STRUJA PREMA 1. KRITERIJU

(BLACKADAR, 1957), IDUĆEG DANA SLABI SMJER VJETRA ZAKREĆE IZ SE U S I SW (1512

m )

• TEMPERATURNA INVERZIJA - OD 955-994 m NAD TLOM UZ OPADANJE TEMPERATURE U TOM SLOJU 3.6 °C/100 m

• PSEUDOTEMP: – MODELIRANE PROCJENE VISINSKIH PROFILA POMOĆU MODELA ALADIN