Numerical simulation of photochemical episodes in alpine valleys
Résumé
Alpine valleys are sensitive to air pollution due to emission sources (traffic, industries, individual heating), morphology (narrow valley surrounded by high ridge), local meteorology (temperature inversions and slope winds). Such situations are rarely investigated with specific research programs taking into account detailed atmospheric chemistry coupling gas and aerosol phases. Following the accident under the Mont Blanc tunnel on March 24th, 1999, international traffic between France and Italy was stopped through the Chamonix Valley (France). The heavy-duty traffic (about 2130 trucks per day) has been diverted to the Maurienne Valley, with up to 4250 trucks per day. The program POVA (Pollution des Vallées Alpines) started in May 2000, with the objective to analyse air quality and develop atmospheric modelling in each of the two valleys, in order to study impact of traffic and local development scenarios.