 |
| Titel |
Network design for ozone monitoring |
| VerfasserIn |
Lin Wu, Marc Bocquet |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048524
|
|
|
|
|
|
| Zusammenfassung |
| Ozone is a harmful air pollutant at ground level, and its concentrations are measured with
routine monitoring networks. In this study, network design based on the ozone monitoring
network over France (BDQA) is conducted by either removing the redundant stations or by
displacing the background stations (e.g. the rural and some suburb stations). The design
methodology is composed of three parts: a geostatistical ozone estimator, a design criterion
and an optimal selection procedure based on simulated annealing. Several spatial
interpolation (kriging) methods have been tested. It is found that statistical information about
the means of ozone concentrations improves significantly the kriging results, and that
it is necessary to consider the correlation model to be hourly-varying and daily
stationary.
In the network reduction problem, we examine how well a subset of the BDQA network
can represent the full network. By this way, the efficiency of the complete BDQA network is
evaluated. Significant improvements can be obtained through optimal reduction. For instance,
removing optimally half the stations leads to an estimation error of the order of
the standard observational error (5Â ppb). In the network displacement problem,
chemistry-transport model (CTM) simulations are used to estimate ozone concentration
where no observations are available. Three types of redistribution criteria are assessed: the
geometrical, geostatistical, and physical ones. The geometrical criteria are of space-filling
type. The geostatistical criteria minimize the kriging error (according to A, D or
E-optimality conditions). The physical criteria aim at best reconstructions of ozone
fields (generated by simulations of a CTM or by data assimilation experiments).
By displacing background stations to regular grid points over France, significant
improvements against the original background BDQA network have been found
under all the proposed criteria. The impact of the different criteria on displacement
is also discussed. The physical criteria are more appropriate for complex design
taking into account the heterogeneity of ozone field. More background stations are
displaced to the coast, frontiers, and large urban agglomerations, e.g. Paris and
Marseilles. |
|
|
|
|
|
|