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Optimisation of CHIMERE configuration in the frame of an ozone
sensitivity study
Fanny Lasry, Isabelle Coll
CHIMERE workshop 21 – 22 March 2005
Problematic
Ozone: harmful pollutant - respiratory troubles - yield decrease
Study focused on the Berre-Marseilles area (South of France), frame of the ESCOMPTE program
Urban area
Industrial area Diversity of the emitters =>
variety of primary compounds
Coastal site => small scale phenomena such as sea-breeze
Action engaged in order to reduce ozone concentrations in the troposphere (Göteborg protocol)
Efficiency of these measures on ozone concentrations?
Strategy
Research of an optimized configuration of CHIMERE in order to simulate ozone episodes in such a complex area
Small scale dynamic(sea breeze phenomenon)
Variety of the emitted compounds
Characteristics of the region Model configuration
Dynamical fieldsECMWF (0.5°) -> RAMS, MM5 (3km)
Emission inventoryGENEMIS -> ESCOMPTE
Chemical mechanismMELCHIOR (44 species) -> SAPRC (80 species)
SAPRC99 (Carter)
“A detailed mechanism for the gas-phase atmospheric reactions of VOCs and NOx in urban and regional atmospheres” (documentation of the SAPRC99 chemical
mechanism for VOC reactivity assessment, Carter, 2000)
- Used to “determine the absolute and relative ozone impact of the many types of VOCs that can be emitted into the atmosphere, and for other control strategy and research applications”
- Used to calculate the various ozone reactivity scales developed by Carter (MIR, 1994)
82 species – 30 VOCs241 reactions
Representation of the radicals chemistry Detailed speciation of VOCs and RO2
Implantation in CHIMERE
Impact of a better resolved dynamic on ozone fields
Boundary layer better resolvedBetter restitution of the sea breeze – wind fields perpendicular to the coast
ECMWF (0.5°) MM5 (3km)
Boundary layer height
ECMWFRAMS
Model overestimationMM5
Impact of a better resolved dynamic on ozone fields
Bias on maximal values
GENEMIS
NOx
VOC
Higher Nox emissions in townHigher biogenic VOCs emissions
ESCOMPTE
Impact of a more accurate emission inventory on ozone fields
GENEMIS ESCOMPTE
Better restitution of the diurnal cycle of ozone: - Better titration by the NOx at night- Increase of ozone maximal values up to 10 ppb locally
Better restitution of primary compounds levels, especially in urban areas
Impact of a more accurate emission inventory on ozone fields
MM5+ESC+MELCHIOR MM5+ESC+SAPRC
Overestimation of ozone maximal values with MELCHIOR: too productive?SAPRC: better scores, less false alert
Impact of the chemical mechanism on ozone fields
Missed alert Correct alert False alert
Success index – 90ppb threshold Success index – 90ppb threshold
Initial configurationECMWF+GENEMIS+MELCHIOR
Scenario configurationMM5+PRIMEQUAL+SAPRC
Final configurationMM5+ESCOMPTE+SAPRC
THANKS FOR YOUR ATTENTION