cen:proj:79399

Ambient air — Definition and use of modelling quality objectives for air quality assessment cen:proj:79399

Scope

This WI defines and describes the methodology to calculate Modelling Quality Objectives (MQO). The method uses measurement uncertainty as a benchmark and relies on a level of stringency (i.e. acceptable level of difference between modelled and measured values) to assess the “modelling quality objectives”, and assure that modelling-based assessments of air quality are objective and comparable, and of sufficient quality to obtain reliable information about concentrations of air pollutants in ambient air.
This WI concerns the performance of an entire modelling system, i.e. a chain of models and sub-models, including emission inventories, meteorological information, atmospheric chemistry and transport modelling for a given application characterised by a specific location and time period; therefore the term “modelling quality objectives” is used rather than just “model quality objectives”. The results of a modelling system shall fulfil the MQO to reach an adequate data quality level within the modelling domain defined for assessment. Assessment is defined as the use of a modelling system to calculate levels of air quality retrospectively, as e.g. in the context of the EU air quality directives.
It should be recognized that the procedures described in this WI are limited in scope as they concern only statistical performance indicators. A full evaluation of the modelling system would have to consider additional elements of quality assurance, but such procedures are outside the scope of this WI.
This WI only addresses modelling applications where measurements of pollutant concentrations are available. MQO apply to all concentration ranges that may occur in ambient air. In the context of this WI, MQO are specified for: daily and annual average concentrations of particulate matter with particle diameter below 2.5 μm (PM2.5), and particulate matter with particle diameter below 10 μm (PM10); hourly and annual average concentrations of nitrogen dioxide (NO2); and maximum 8 hour daily and annual average concentrations of ozone (O3). This WI will also suggest procedures to extend the application of MQO to other pollutants and time averages, through methods to develop measurement uncertainty parameters for those pollutants and time averages
This WI does not detail all conditions under which the MQO methodology applies and it does not detail the associated metadata information, required to ensure replicability. This is discussed in other documents, in particular in FAIRMODE guidance document.

Related legislation

Legislation related to this standard