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