Title of Example

Example

Introduction

The PM₁₀ and O₃ Forecast Bulletins for the Veneto region have been conceived as a tool of daily information to the population on the current state of air quality, especially in the areas around the provincial capital cities. PM₁₀ and O₃ are the most relevant pollutants that exceed the Limit values, PM₁₀ during winter time (exceedances of the 50 mg/m³ LV), and O₃ during summer season (exceedances of the 180 mg/m³ national LV). This information is particularly relevant to some parts of the population, like people suffering from asthma or other respiratory symptoms, cardiopathics, children, child-bearing women, and elder people. Secondly and more fundamentally, this pollutant monitoring is the basis for Local Authorities to enforce the LVs as defined by the law.

Figure 1 - PM₁₀ and Ozone Bulletins format.

Zones and levels

The Veneto Region has complex orography and morphology, including high mountains, hills, big lakes, large rivers, spacious forests, and the Venetian Lagoon. The plains are densely populated: here people live concentrated in seven major cities, while the mountain areas are under populated. Distances from the Adriatic seaside to the Dolomite mountains are 100 km or less.

These Bulletins do not cover the mountain area as it is too sparsely covered with observing meteorological stations. The plains, on the other hand, are divided into four areas, each one exhibiting relatively homogenous climates and air quality conditions. These regions are depicted in Figure 2 and comprise 1) the inner plains with the provincial capital cities of Verona, Vicenza, and Padua, 2) the area along the Po river including the provincial capital city of Rovigo, 3) the Adriatic coast line including Venice, Mestre, and Marghera, and 4) the North-east hills region including Treviso.

In order to provide a direct and immediate information to the population, a four-level colour coding has been devised rather than issuing numerical values for the pollutant concentrations. The scheme uses different nuances of blue to denote increasing danger for people’s health.

Figure 2 - Zones and classes of Air Quality Forecast (AQF). Light blue means Fair AQF, grey-blue means Poor, while darker blue means Very Bad.

Forecast methodology

The pollution Forecast Bulletin is subjective and based on the following steps:

- Analysis of current air quality situation including concentration of pollutants in the atmosphere. Seven provincial departments of ARPAV (Veneto Region Environmental Protection Agency) manage the air quality network, consisting of about 30 automatic sampler stations, some of them located in hot spots close to the city centres, some other in rural areas providing information on the background state of pollution in the region. These departments perform quality control on the data set too, along with preliminary statistical analyses.

Figure 3 - Today situation

- Air quality evolution over the last ten days. For certain stable meteorological conditions, both PM₁₀ and O₃ show a persistent behaviour with a tendency to accumulate over time. In order to estimate residence times of pollutants, historical data analysis would be helpful, but such data reach back only a few years in our network.

Figure 4 - Last days situation

- Chemical Transport Model CHIMERE, developed at the Ecole Polytecnique of Paris. CHIMERE is run on a European-wide area, and makes use of mesoscale numerical weather prediction (NWP) data (MM5), including wind, temperature and other variables.

Figure 5 - CHIMERE output

- Subjective prediction. This final step of the forecast process leading to the Bulletins draft is still the main part of the final forecast. Co-operation with the CMT (ARPAV Regional Meteorological Centre) Forecast Office, including inspection of global and limited area NWP products, radar and satellite imagery, and surface data from the roughly 200 CMT surface stations, leads to the assessment of the pollutants temporal trend. The meteorological conditions are often determinant for the concentrations evolution (radiation, temperature and wind conditions for Ozone trends; rain, wind and mixing height conditions for PM₁₀ trends), and therefore for the final definition of the pollution level in the Forecast Bulletin.

General information

The Ozone Bulletin was first issued in the summer 2003, while the PM₁₀ Bulletin followed in the winter of the same year. The CMT PM₁₀ and O₃ Forecast Bulletins are delivered Monday through to Friday, while Saturdays and Sundays are covered only in special cases (episodes of acute pollution). They have been evaluated to have a good reliability as predictions are correct around 70% of the time on average for the emission day and around 60% for day plus one. Gross errors like “over estimation” or “false alarms” are under the 10% on average.

In 2004 these Bulletins and the real-time dissemination of air quality monitoring data have received the congratulations from the European Commission

For more information about this products, please contact CMT: cmt@arpa.veneto.it

Useful links

ARPA Veneto and CMT: http://www.arpa.veneto.it/

Ècole Polytechnique : http://www.polytechnique.fr/

CHIMERE: http://euler.lmd.polytechnique.fr/pioneer/forecasts/index.html

MM5: http://www.mmm.ucar.edu/mm5/mm5-home.html

Acknowledgements

This text has been prepared by ARPAV – CMT (ARPAV Regional Meteorological Centre), dr. Massimo Ferrario.

Last Updated

25th January 2005