1. FOREST FIRE IMPACT ON AIR QUALITY THE LANCON-DE-PROVENCE 2005 CASE S. Strada, C. Mari Laboratoire d'Aérologie, Université de Toulouse, CNRS, Toulouse, France J.B. Fillipi, F. Bosseur SPE, Università di Corsica, CNRS, Corte, France 8 th Symposium on Fire and Forest Meteorology – Kalispell,

2. Forest Fire and Air Quality A brief introduction Forest Fires in mediterranean region More frequent ignition Widening of areas at risk Air pollution alerts Coupled Atmosphere-Wildfire Modeling Meso-NH & ForeFire To investigate fire dynamics and chemistry and atmospheric feedbacks A case study Lançon-de-Provence (France) 2005 A typical mediterranean wildfire in a complex topography

3. Atmospheric model: Meso-NH Configuration: Two-way grid nesting: 25km, 5km, 1km, 200m ECMWF reanalysis 72 levels up to 23 km dx = 40 m near the surface, dx = 600 m at the top Version 4_7_4 Activated schemes: Microphysics: ICE3 Turbulence: 1D & 3D (200m)‏ Advection: PPM Surface: ISBA Chemical scheme with 40 chemical species and 73 chemical reactions (Relacs)‏

4. Fire Spread Model: ForeFire Model features Analytical formulation of RoS Front tracking algorithm Coupled Atmosphere-Fire Modeling Fire as subgrid scale process One-way coupling through ISBA scheme Radiative temperature, heating and water vapor fluxes as inputs for Meso-NH at each model timestep -> fraction of area burnt provided by Forefire -> gridded through the PGD program

5. The Lançon-de-Provence case study Fire features Date: July 1, 2005 Time: 09:40 LT -> 17:40 LT On fire: 626 ha of scrublands (garrigue)‏ In danger: downwind inhabited areas and cultivated lands A typical meteorological situation: the Mistral Strong northwesterly wind favoured by a strong pressure gradient over Western Europe and a tunnel orographic effect

6. Fire impact on atmospheric dynamics Fire vs. no fire simulation at dx=1 km Wind speed difference at the surface (m/s) Fire tracer @ 500 m

7. Fire impact on ozone chemistry Fire vs. background concentrations at dx=1 km Emissions: Ei = EFi x x B x Efi = Emission factors [g/kg] = Glocal burning efficiency B = Fuel load (kg/m 2 ) = burnt area (m 2 )‏ Forefire ! [NO2] fire - [NO2] background @ 500 m [O3] fire – [O3] background @ 500 m

8. Conclusions Sensitivity of the dynamics and tracer transport to the coupling -> fire-induced surface winds -> fire emissions injection height particularly sensitive to fire heat fluxes: latent + sensible Effective fire impact several hundreds of kilometers downwind of the burnt area Well marked chemical plume with high concentrations of CO, NOx, VOCs and a contrasted ozone signature near and downwind of the fire

9. Perspectives Work in progress on simulation with the coupled model at 200 m resolution (IDRIS - Vargas)‏ Comparison with ASQA database Refine emission factors for the mediterranean ecosystems (LA & SPE) – On-line implementation in ISBA‏ Test the EDKF scheme on the same case. Two-way coupling Meso-NH & Forefire (ANR IDEA)‏