Comparison of chemical schemes used in photochemical modelling - Swedish conditions

摘要

The compressed chemical description used in three internationally well-known models, i.e. the EMEP, CBM-IV and RADM-II models were set up in a model frame being representative for Swedish conditions. The results from the use of these compressed chemical schemes were compared with the results when an explicit scheme with a high level of detail i.e. the IVL model in the 1995 version, was used in the same model set-up. In addition, a new approach to compressed chemical modelling was presented, based on the Photochemical Ozone Creation Potential (POCP), and the results were compared with the results from the well established compressed schemes. The compressed scheme used in the EMEP model (1993 version), including some minor modifications in order to make the models strictly comparable, was seen to be in good to excellent agreement with the results from the IVL model for most of the studied scenarios. For two-day simulations the CBM-IV scheme also gave results very close to the IVL model. For scenarios describing very NO(sub x) limited conditions including high VOC conditions, the POCP and CBM-IV schemes were in closer agreement with the IVL model results than the EMEP model was. The 50% VOC Swedish emission reduction scenarios gave peak ozone reductions of 3-4 ppb (6-7%) as simulated by the IVL model for summer conditions. The corresponding PAN reduction was 0.2-0.3 ppb (ca 40%). The 50% NO(sub x) emission reduction gave 5-6 ppb (ca 10%) ozone reductions and 0.1-0.2 (ca 20%) PAN reductions. A combined reduction of 50% VOC and NO(sub x) emissions gave 7-9 ppb (ca 15%) ozone reductions and 0.3-0.4 (45-50%) PAN reductions. 26 refs, 7 figs, 7 tabs