Making better air quality forecasts
Air quality models apply numerical methods to basic atmospheric physics and chemistry. These models require rigorous amounts of input data in order to produce a good result. Apart from meteorological and pollutant emissions data, the other main input required are chemical reaction rates. Chemical reaction rates tell us how easily different molecules in the atmosphere will combine (or break apart). We are most interested in the pollutant molecules, those that affect the quality of the air we breathe. This, combined with knowledge of emissions of these pollutants, can tell us what kind of air quality problems to expect. One of the objectives of the CATOME project, sponsored by the ENV 2C Programme, was to increase the knowledge base of chemical reaction rates. A consortium of research partners performed laboratory experiments to determine chemical reaction rate coefficients for hydroxide (OH) and nitrate (NO3). OH and NO3 are essential radicals in the earth's atmosphere. Both of these radicals play an important role in the creation of ozone (i.e. smog) and acid rain. Reactions rates for OH and NO3 were established for 20 aldehydes using the relative rate method. The results were incorporated into the Master Chemical Mechanism (MCM) for use in air quality models. The MCM was verified using an air quality model for a test case in Norway with very good results. The results of this work are particularly promising for environmental monitoring and planning. The consortium is looking to disseminate the findings to a wide audience.
