Measurement values of hourly ozone data ordered by station from 1990 are available. There are a few changes in the following set of source-receptor matrices calculated with the Lagrangian photooxidant model, compared to the tables in EMEP Summary Report 2/00. The officially submitted emission estimates [EMEP/MSC-W Note 1/00] for the Year 2010 have in a number of cases changed substantially from those used in the previous EMEP report, EMEP Summary Report 2/99 , and Iceland should not have been in the list of receiver countries.
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Source-receptor (S-R) relationships give the change in ozone in each receptor country (or grid square) resulting from a change in emissions of either NOx or VOC from each emitter country. They are generated for each country by reducing either NOx or NMVOC emissions (anthropogenic) by a given percentage from that country, re-running the oxidant model, and comparing the resulting fields of ozone or AOTs with the base-case fields.
The first full set of such S-R matrices was presented in [Simpson et al.(1997)], where calculations were performed with the Lagrangian oxidant model for a 5 year period: 1989, 90, 92, 93, 94. A number of matrices with different assumptions (including 40% reductions) were calculated in order to supply results needed for the IIASA RAINS-ozone model [Schöpp et al.(1999)]. Extensive discussions of the behaviour of source-receptor matrices for ozone, and of the extent of linearity of these, have been presented elsewhere [Simpson(1991),Simpson and Malik(1996),Simpson et al.(1997)].
Unfortunately the model domain of the Lagrangian has not yet been extended to cover the territories of all new Parties to the Convention, so we cannot present source-receptor calculations for these countries. This problem will be solved in future reports by performing such calculations with the 3-D Eulerian models with the extended domain.
The basic methodology used to calculate S-R matrices is identical to that of Simpson and Jonson (1999) with calculations performed for 40% emission reductions. The base-emission case is for the year 2010, using the EMEP emissions estimates as given in [Vestreng and Støren(2000)]. The meteorology for the 5-year calculations is from April-September of 1992, 93, 94, 95 and 96.
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A number of man made pollutants, as nitrogen oxides and volatile organic compounds (VOC), that can affect the photochemical activity, are emitted into atmosphere. Nitrogen oxides are emitted mainly from combustion processes from both mobile sources (ie road traffic) or stationary sources (ie power plants). VOC are emitted from combustion and also by evaporation of fuels and solvents. Furthermore natural emissions, in particular of hydrocarbon from trees, will also contribute to the photochemical activity.
In the atmosphere these pollutants may react, producing other toxic pollutants (mainly ozone). The production of ozone require sunlight. Therefore ozone above what is considered harmful for the environment or for humans is mostly a problem in the summer months. Both observations and calculations have shown that ozone has increased over the last decades in Europe. Moreover, increasing evidence also show that ozone has increased by approximately a factor of two throughout the lower atmosphere in the northern mid latitudes since early this century.
Exeedances of ozone considered harmful for humans and for the environment is most frequent in central and southern parts of Europe. Close to the surface nitrogen ozidants, hydrocarbons and ozone itself can build up in what is called ozone episodes. In northern parts of Europe Exeedances are not as frequent mainly because the solar radiation is weaker further north.
To avoid such pollution events emissions must be reduced. However the chemical mechanisms involved are complicated and there are still uncertainties as to how reductions should be made cost effective (The maximum amount of reductions for a given sum of money). In particular for nitrogen oxides reductions are desirable also for other environmental reasons as acidification and eutrofication.