Development of an Air Quality Information System

Development of an Air Quality Information System (the AirQUIS System), including an Urban Scale Model Evaluation/Validation Exercise.

A contribution to the subproject SATURN

Steinar Larssen, Trond Bοhler and Sam Erik Walker

Norwegian Institute for Air Research, P.O. Box 100, N-2007 Kjeller, Norway

Summary

The research in this contribution to SATURN has in 1998 concentrated on the development of version 2 of the AirQUIS air quality information and management system, as well as on the testing of the NILU urban airshed model EPISODE on the Oslo data base, which we intend to offer for use in a urban model intercomparison study in 1999.

Aim of the research

The main objectives of this contribution are:

to develop and demonstrate a GIS-based air quality information system that includes provisions for handling monitoring data and dispersion modeling, and methods for exposure calculations.
to organize an urban scale evaluation/validation exercise based upon the Oslo database.

Activities during 1998

This contribution involves the following activities in this SATURN subproject:

Activity No. 33: Specifications for pollutant concentrations in the field.

Objectives: - Develop specs for AQ data to be used for evaluation/validation of models;

- Setting up the Oslo data base for validation exercise.

Activity No. 42: Oslo emission inventory: Make it available for model validation exercise.

Activity No. 51: Model validation exercise based upon Oslo data

Activities No. 72 and 80: Integration of models for emissions, transformation and dispersion to a versatile tool for air quality management (AirQUIS): To develop and demonstrate AirQUIS, for use by local air quality management authorities. Activity No. 84: Development of an efficient method for exposure calculations.

The project activities in 1998 has concentrated on the AirQUIS system development, and evaluation of the NILU EPISODE urban airshed model on Oslo data.

Principal results

AirQUIS development

Introduction

The ENSIS group, consisting of the Norwegian Institute for Air Research, Norwegian Institute for Water Research and The Norgit Center, has developed an Environmental Surveillance and Information System (ENSIS) consisting of three modules; AirQUIS, WaterQUIS and CorrCost with treats air pollution, water pollution and damage to materials, respectively.

The AirQUIS System

The air quality part of ENSIS, AirQUIS, includes (see picture on next page):

A manual and automatic data entering application,
An on line monitoring system,
A measurement data base for meteorology and air quality,
A modern consumption/emission inventory data base with emission models,
Numerical models for transport and dispersion in air of pollutants,
An effect module for population exposure,
statistical treatment and graphical presentation of measurements and modelling results,
An user friendly menu and map oriented interface,
Import/export wizards for import of data and dissemination of results.

All objects described above is integrated in a map and menu oriented, user friendly interface with direct link to the data bases for measurements and emissions and presentation tools. Advanced import/export wizards allows the user easy to transfer data to and from the AirQUIS system (Bοhler et al., 1998).

Monitors, data acquisition and quality control

The AirQUIS system can include an existing monitoring network by adapting the protocols for data exchange or select the monitors used by NILU. Specially designed flexible data loggers have been developed to collect and store data from different types of monitors. An automatic data acquisition system (ADACS) has been developed for collection of data directly from the monitors and into the AirQUIS Measurement Database. Quality control is performed at the stations during automatic and manual calibrations and in the central data base following ISO quality assurance routines.

The emission inventory database

A modern data base for emissions to air has been developed. The emission module is a flexible system containing a map oriented interface to treat the sources for emissions to air such as industry, traffic, airport and harbour activities and domestic energy consumption. The sources can be selected either by activity, or area distribution. The traffic module is the most complex part of the emission module, taking into account variables such as road type, facades, vehicle type, driving speed and traffic time variation.

Atmospheric dispersion models

The dispersion models in AirQUIS covers air pollution on all scales in the urban environment; road traffic, industrial emissions and emissions from household. The NILU developed model EPISODE calculates spatial distribution of hourly concentrations of the main air pollution components in the urban atmosphere. The NILU model CONTILINK is used to estimate sub grid concentrations close to roads within the square grid. A puff-trajectory model is used to calculate the impact from point sources.

Air Quality Indicators, and population exposure

Many national and international authorities are working with selection of environmental indicators. The indicators form a basis for evaluating the impact on humans and the environment as a whole. A set of indicators based on combination of measurements and model results can be established in the AirQUIS system. These indicators may be a single parameter or derived from a set of variables, both modelled and measured, to reflect the status of the environment. One type of indicator, the population exposure type, is included in the form of a module for calculation of the exposure.

Planning and decision-making tool

The system can also be used as a planning and decision tool, by evaluating the effect of reduced air pollution related to different measures. The effects of changing the road network or new establishment of industry can be evaluated by changing the input in the emission module and calculate the concentration distribution by using the air quality dispersion model for the area.

The platform

The AirQUIS system version 2.0 is a Client-Server system, developed for the Windows NT platform, and running on IBM compatible Pentium or Pentium Pro PCs. The data base system is Oracle and the integrated geographical information system is based on Map Objects from ESRI and implements a map oriented platform directly linked to all modules.

Installations

The AirQUIS system has been installed in the major cities in Norway. In addition, installation in three cities in China will be performed this year. In India, Saudi Arabia, Egypt and Botswana, the authorities evaluates to use AirQUIS as the national air quality system for both measurements and emissions to air from traffic, industry and household. ENSIS is also the demonstrator in the EU TAP project IRENIE. Several other clients have contacted NILU to discuss further the implementation of AirQUIS.

AIRQUIS Concept and Modules.

EPISODE evaluation

Partly as a preparation for the model intercomparison exercise on the Oslo data base, the NILU EPISODE model was recently evaluated on Oslo data.The air pollution dispersion model EPISODE has been developed at NILU during several years (Walker, 1997). Earlier versions of the model have been applied in several places both in Norway and elsewhere (Larssen et al., 1994), (Grοnskei et al., 1993). Here are described some results from the most recent evaluations of the model for NOx and NO2 at an urban background station in Oslo (Slοrdal and Walker, 1997) for the period 1 October 1996 - 19 November 1996.

The model is described in Walker et.al. (1998), as well as brief descriptions of input data on emissions and meteorology.

Results and discussion

Overall, observed and model calculated concentrations corresponded fairly well during the evaluation period 1.10.96 - 19.11.96 (1198 hours), see Figure 1. Correlation between observed and predicted values for NOx (and NO2) was found to be 0.73 (and 0.68) with mean values of 88.8 mg/m3 (obs.) and 83.1 mg/m3 (pred.) for NOx and 38.5 mg/m3 (obs.) and 35.9 mg/m3 (pred.) for NO2. Sensitivity analysis indicates that the deviations between observed and predicted concentrations, to a large extent can be explained by the non-representativeness of using only the observed thermal stability DT at station Valle Hovin (outside of city centre) as a measure of the stability conditions in the city centre (at the station Nordahl Brunsgt).

Fig. 1 Observed and model calculated hourly concentrations of NOx and NO2 at station Nordahl Brunsgt. in Oslo for a part of the evaluation period containing highest concentrations.

Main conclusions

The AirQUIS system, version 2.0 has been developed during 1998, and a prerelease version is now being used in thorough testing.

The EPISODE model has been shown to simulate NOx, and NO2, concentrations in Oslo well, using the Oslo data base.

Aims for the coming year

The main activities to be carried out in 1999 are:

AirQUIS: We intend to contact selected cities in Europe, their AQ management authorities, and demonstrate AirQUIS as a tool in their city. The selected cities must have a spatial/temporal emissions data base in place, and a functioning meteorological and AQ monitoring system.

We also intend to further the work on population exposure models and calculations.

Model intercomparison: We intend to offer the Oslo data base as a basis for an urban model intercomparison exercise.

These activities are dependent upon sufficient funding.

References

Bοhler T., B. Sivertsen; A modern Air Quality Management system used in Norway, NILU F 4/98, Norwegian Institute for Air Research, Kjeller (1998).

Bοhler T., A. Riise; Using the air quality assessment system AirQUIS in modelling the population’s exposure to traffic induced air pollution, NILU F 7/97, Norwegian Institute for Air Research, Kjeller, (1997).

Bοhler, T.; Environmental surveillance and information system. Presented at the Air Pollution 95 Conference, Porto Carras September 26-29, 1995, NILU F 13/95 Norwegian Institute for Air Research, Lillestrοm (1995).

Grοnskei, K.E., S.E. Walker, F. Gram; Atmos. Environ. 27B (1993) 105-120.

Larssen, S., K.E. Grοnskei, F. Gram, L.O. Hagen, S.E. Walker; Verification of urban scale time dependent dispersion model with subgrid elements in Oslo, Norway, in: S.-E. Gryning, M.M. Millan (eds) Air Pollution Modelling and Its Application X, Plenum Press New York (1994), pp. 91-99.

Slοrdal, L.H., S.E. Walker; Dispersion calculations of NOx, NO2 and PM10 in Oslo, Drammen, Bergen and Trondheim. Model validation. NILU OR 68/97, Norwegian Institute for Air Research, Kjeller (1997) (in Norwegian).

Walker, S.E.; The EPISODE air pollution dispersion model, version 2.2. Users Guide, NILU TR 10/97, Norwegian Institute for Air Research, Kjeller (1997).

Walker, S.E. L.H. Slοrdal, C. Guerreiro, K.E. Grοnskei, S. Solberg; Development and Evaluation of the Urban Dispersion Model Episode, in P.M. Borrell and P. Borrell (eds.) Proceedings of EUROTRAC Symposium '98, WIR Press, Southampton (1998), pp. 9-12(1)-9-12(4).