Effects of various meteorological conditions and spatial emissionresolutions on the ozone concentration and ROG/NOx limitationin the Milan area (I)

[摘要] The three-dimensional photochemical model UAM-V is used to investigate theeffects of various meteorological conditions and of the coarseness ofemission inventories on the ozone concentration and ROG/NO_x limitationof the ozone production in the Po Basin in the northern part of Italy. As abase case, the high ozone episode with up to 200ppb on 13 May 1998 wasmodelled and previously thoroughly evaluated with measurements gained duringa large field experiment. Systematic variations in meteorology are appliedto mixing height, air temperature, specific humidity and wind speed. Threecoarser emission inventories are obtained by resampling from 3x3km² upto 54x54km² emission grids. The model results show that changes inmeteorological input files strongly influence ozone in this area. Forinstance, temperature changes peak ozone by 10.1ppb/°C and the ozoneconcentrations in Milan by 2.8ppb/°C. The net ozone formation innorthern Italy is more strongly temperature than humidity dependent, whilethe humidity is very important for the ROG/NO_x limitation of the ozoneproduction. For all meteorological changes (e.g. doubling the mixingheight), the modelled peak ozone remains ROG limited. A strong changetowards NO_x sensitivity in the ROG limited areas is only found if muchcoarser emission inventories were applied. Increasing ROG limited areas withincreasing wind speed are found, because the ROG limited ozone chemistryinduced by point sources is spread over a larger area. Simulations withoutpoint sources tend to increase the NO_x limited areas.

[学科分类] 大气科学