Production of ozone in the Chamonix Valley (France)
Résumé
In the framework of the POVA program a numerical investigation aims to better understand how a reduction of traffic emissions can affect air quality in the Chamonix valley (France). The MM5 model coupled with the Chemistry Transport Model (CTM) TAPOM using a 1 km-cell grid for the period 5-12 July 2003 showed that the ozone formation in the Chamonix valley was strongly NOx-saturated. A comparison with physical and chemical measurements (tethered balloon, UHF radar, monitoring data) prove the temperature profile and the up-and downhill thermally-driven winds to be reasonably well described by MM5. Moreover spatial and temporal variation of O 3 concentration is well described by TAPOM. Ozone production within the valley is estimated to 20 to 30 µg/m 3 and 10 µg/m 3 are locally produced from precursors emitted by international traffic through the tunnel.