3.2.2 State
STATE, in the DPSIR approach, is defined as the environmental conditions of a
natural system; in the current case, it represents the concentrations of targeted
pollutant in atmosphere.
Air quality state can be described as gridded concentrations over the studied
area, or as local concentrations at receptor sites. The AQ state has also a temporal
dimension, considering that a pollutant can be monitored or modelled with different
temporal resolutions.
A large variety of chemical transport models exist, implementing from simpler to
more complex approaches and covering different scales, going from global/regional
scales to urban and street level scales. State can be also described by source-/
receptor models that directly link the emission to an AQ index calculated from
targeted pollutant concentrations.
The APPRAISAL database indicates that national, regional and local authorities
use a large variety of air quality models to design their AQPs and assess their
impacts on air quality.
If we analyze the responses in terms of model types, Eulerian models are the
most used with 32 and 59 % for AQP and RP, respectively (Fig. 3.3) which is not
surprising since Eulerian modelling can be applied from the regional down to the
local scale. In the case of AQPs, Gaussian plume and puff approaches represent
about 20 %, in total while in RPs they represent only 6 % of use cases.
In total 33 different model names are mentioned. The most popular are the
Eulerian models CAMx with 8 citations and CHIMERE with 11. CALPUFF is
cited 6 times in the sample, but also traffic models are included (IMMIS, PROKAS
and OSPM) with more than 5 citations. The many different models that are used
today are a clear indication that no standard reference model currently exists. It is
also interesting to note that in many AQPs, more than one model is used: three or
more are used in 33 % of the cases, while about 27 % of the AQPs refer the use of
two models and about 44 % of a single model. Regarding research projects, a
unique model is used in 44 % of the cases, two in 17 % and three or more in 39 %
of the cases sampled. In these projects, CHIMERE is the most often used chemical
transport model. It is important to stress however that in one reported case, no air
quality model is used. Information about modelling methodologies is in general
available since approximately 70 and 85 % of the models referred to by the
APPRAISAL database contributors are included in the EEA Model Documentation
System, for AQPs and RPs, respectively.
It is interesting to note that street canyon models are not so frequently used
(12 % in AQP). This is probably due to the lack of proper input data at the adequate
resolution, or to the limited spatial coverage these models generally have. One can
also note that CFD models are rarely used in Europe even in research projects,
probably due to their current limitation to idealized, stationary and very fine scale
applications. Calculation of annual statistics therefore still remains a very
42
C. Belis et al.
STATE, in the DPSIR approach, is defined as the environmental conditions of a
natural system; in the current case, it represents the concentrations of targeted
pollutant in atmosphere.
Air quality state can be described as gridded concentrations over the studied
area, or as local concentrations at receptor sites. The AQ state has also a temporal
dimension, considering that a pollutant can be monitored or modelled with different
temporal resolutions.
A large variety of chemical transport models exist, implementing from simpler to
more complex approaches and covering different scales, going from global/regional
scales to urban and street level scales. State can be also described by source-/
receptor models that directly link the emission to an AQ index calculated from
targeted pollutant concentrations.
The APPRAISAL database indicates that national, regional and local authorities
use a large variety of air quality models to design their AQPs and assess their
impacts on air quality.
If we analyze the responses in terms of model types, Eulerian models are the
most used with 32 and 59 % for AQP and RP, respectively (Fig. 3.3) which is not
surprising since Eulerian modelling can be applied from the regional down to the
local scale. In the case of AQPs, Gaussian plume and puff approaches represent
about 20 %, in total while in RPs they represent only 6 % of use cases.
In total 33 different model names are mentioned. The most popular are the
Eulerian models CAMx with 8 citations and CHIMERE with 11. CALPUFF is
cited 6 times in the sample, but also traffic models are included (IMMIS, PROKAS
and OSPM) with more than 5 citations. The many different models that are used
today are a clear indication that no standard reference model currently exists. It is
also interesting to note that in many AQPs, more than one model is used: three or
more are used in 33 % of the cases, while about 27 % of the AQPs refer the use of
two models and about 44 % of a single model. Regarding research projects, a
unique model is used in 44 % of the cases, two in 17 % and three or more in 39 %
of the cases sampled. In these projects, CHIMERE is the most often used chemical
transport model. It is important to stress however that in one reported case, no air
quality model is used. Information about modelling methodologies is in general
available since approximately 70 and 85 % of the models referred to by the
APPRAISAL database contributors are included in the EEA Model Documentation
System, for AQPs and RPs, respectively.
It is interesting to note that street canyon models are not so frequently used
(12 % in AQP). This is probably due to the lack of proper input data at the adequate
resolution, or to the limited spatial coverage these models generally have. One can
also note that CFD models are rarely used in Europe even in research projects,
probably due to their current limitation to idealized, stationary and very fine scale
applications. Calculation of annual statistics therefore still remains a very
42
C. Belis et al.