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Aerosol distribution over the western Mediterranean basin during a Mistral event

Aerosol distribution over the western Mediterranean basin during a Mistral event. Salameh T., Drobinski P., Menut L., Bessagnet B., Flamant C., Hodzic A., Moulin C., Vautard R. Scientific motivation. Aerosols over the western Mediterranean basin sources:

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Aerosol distribution over the western Mediterranean basin during a Mistral event

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  1. Aerosol distribution over the western Mediterranean basin during a Mistral event Salameh T., Drobinski P., Menut L., Bessagnet B., Flamant C., Hodzic A., Moulin C., Vautard R.

  2. Scientific motivation • Aerosols over the western Mediterranean basin • sources: • regional: from western and eastern Europe (e.g. Sciare et al. 2003; Traub et al. 2003; Schneider et al. 2004) and from Saharan desert (e.g. Bergametti et al. 1992; Moulin et al. 1998; Guieu et al. 2002) • linked to large-scale phenomena (Moulin et al. 1997) • emissions: urban and industrial, transportation, forest fires, saharan dust, sea… • potential impact on precipitation, radiation, air quality and ecosystems (Lelieveld et al. 2002) • Frequent occurrence of Mistral events (5-15 days/month) pre-conditioned by cyclogenesis over the Gulf of Genoa and the passage of a trough over Europe • extend as far as few hundreds of kilometers offshore (Jansa 1987) and advect pollution over long distances (Corsmeier et al. 2005) • associated with low continental pollution (Bastin et al. 2006) What is the aerosol distribution over the western Mediterranean during a Mistral event?

  3. The March 24, 1998 Mistral event: the dataset • The context: the FETCH experiment • Investigation of air/sea exchanges in a coastal environment under strong wind conditions (Hauser et al. 2003) • Special observation period : March 12 to April 15, 1998 March 24, 1998: well documented Mistral event (Flamant et al. 2003) • The dataset • Above the Mediterranean Sea • Radiosoundings (launched from the RV Atalante) • Airborne measurements (lidar, in-situ measurements) • Shipborne in-situ measurements and buoys • Satellite data (AMI-Wind/ERS and SeaWifs) • Above the continent • Operational meteorological surface stations • Operational radiosounding (Lyon, Nîmes, Ajaccio)

  4. MM5 model (Grell et al. 1995) Initial & boundary conditions ERA-40 Three nested domains 43 sigma levels Domain 1: 50x50 points, 27 km Domain 2: 82x82 points, 9 km Domain 3: 58x40 points, 3 km Mesoscale dynamical and chemical simulations of the March 24, 1998 Mistral event • Chemistry transport model CHIMERE (Schmidt et al. 2001) • 12 vertical levels (surface-500 HPa) • EMEP emissions • Initial & boundary conditions from LMDZ-INCA (gas) and GOCART (aerosols)

  5. NO PPM-coarse particles Urban & industrial sources SO2 CO Ships Aerosol emission sources (EMEP inventory) + saharan dusts (not shown)

  6. MM5 quantitative validation: near-surface data Over the Mediterranean Sea Over the continent 10-m wind and 2-m temperature from the Météo-France meteorological operational network 10-m wind from AMI-Wind

  7. MM5 quantitative validation: vertical profiles Radiosoundings Lyon (continent) Nîmes (continent) RV Atalante (Mediterranean Sea, Gulf of Lion)

  8. March 24, 1998 synoptic environment 0900 UTC 0600 UTC Tramontane Mistral Sheltered region associated with the western Alps wake (gravity wave breaking and wall separation in the western Alps wake, Drobinski et al. 2005) 1200 UTC 1500 UTC 1800 UTC 2100 UTC Ligurian outflow

  9. Aerosol loading on March 24, 1998 Aerosol distribution over the western Mediterranean basin 0900 UTC 0600 UTC Local emissions from the region of Toulon + aerosol plume transported from northern Italy 1500 UTC 1200 UTC Aerosols transported from northern France and channeled in the Rhône valley (Mistral) 2100 UTC 1800 UTC Absence of lateral exchanges between the plumes transported by the Mistral and the Ligurian outflow (despite gravity wave breaking and wall separation induced turbulence)

  10. Zoom on the Gulf of Lion (1100 UTC):comparison with SeaWifs imagery C A F E AF, FC and CE: Legs of the ARAT aircraft carrying LEANDRE-2 lidar Advection from southwestern and northern France through the Aude valley (Tramontane) Advection along the Rhône valley (Mistral) and from northern Italy (Ligurian outflow)

  11. Zoom on the Gulf of Lion (1800 UTC):comparison with LEANDRE 2 Lidar, leg AF CHIMERE Atmospheric reflectivity LEANDRE-2 Atmospheric Reflectivity Long-range transport Aerosol-free region Fos-Berre plume

  12. Conclusion and perspectives • Conclusion • Unsteady event: in addition to the local plumes, the aerosol distribution over the western Mediterranean is dominated by: • the plume transported along the Aude valley by the Tramontane flow during the morning period • the plume from central/northern France channeled within the Rhône valley by the Mistral, and the plume advected by the Ligurian outflow composed of the industrial and urban emissions from Milano • Over Toulon, the absence of wind in the sheltered area is associated with aerosol stagnation (from local origin and from past Milano plume) • Future prospects • Representativity of this case: classification typical aerosol distribution associated with all typical Mediterranean weather regimes (including Mistral)

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