VALIDATION OF MESOSCALE METEOROLOGICAL SIMULATION OVER PO VALLEY FOR AIR QUALITY APPLICATIONS

Very high ground level concentrations of PM in winter and of ozone in summer often occur in Northern Italy, due to the high anthropogenic emissions and frequent stagnant meteorological conditions that characterize the area. These problems are not only related to urban, but also to suburban areas through the entire Po Valley. In such a situation it is important to use deterministic Chemical Transport Models, that allows to evaluate the effect of different air quality control policies on secondary pollution concentrations. Chemical Transport Models generally are part of more complex deterministic modelling systems, encompassing also emission models, meteorological models, and initial and boundary condition processors. Meteorological models are an important module of deterministic modelling systems and, due to their complexity, require high computational costs to perform simulations. In fact they solve a full set of non-hydrostatic equations that describe atmospheric dynamics and thermodynamics, and conservation equations, usually considering two-way interacting nested domains. Within the HPC-EUROPA (Pan-European Research Infrastructure on High Performance Computing) cooperation project, that allows to use clusters of CPUs all around Europe, the meteorological fields over Northern Italy were simulated using RAMS4.4 in parallel mode, creating a database for future air quality assessments. In the present work a CPUs cluster of the Italian computing centre CINECA have been used. The meteorological simulations have been performed considering three nested grids. The first grid covers an area that encompasses the entire Europe, the second grid is focused on Mediterranean sea, while the third one is limited to the Po Valley area. The spatial resolution of the three grids is respectively 128 km, 32 km and 8 km. The number of cells for the three grids is respectively 40x40, 86x86 and 102x102, with 33 vertical levels covering the domain from surface to roughly 20 km height. The entire 2004 year has been simulated through 72 simulations of 126 hours each, considering a spin-up time of 6 hours and 16 CPUs each simulation. In this paper the model configuration and the validation of the simulated meteorological fields are presented

COMBINED USE OF SPACE-BORNE OBSERVATIONS OF NO2 AND REGIONAL CTM MODEL FOR AIR QUALITY MONITORING IN NORTHERN ITALY

The use of space-borne measurements of trace gas constituents for air quality monitoring is considerably increased during the past decade. This is due mainly to the new generation sensors able to observe large areas with good temporal resolution and due to new assimilation techniques that allow a synergetic use of information from satellite and from Chemical Transport Models (CTM). In fact the in situ sampling method used by the local environmental agencies for air quality monitoring is becoming too expensive to be further continued without a sensible reduction in the number of observing stations. In this paper we present the work that has been performed so far within the QUITSAT project funded by the Italian Space Agency. SCIAMACHY (Uv-Vis spectrometer on board ESA-ENVISAT platform from 2002) observations of earth radiance are used to retrieve NO2 tropospheric column by DOAS spectrometric technique and radiative transfer modelling for AMF computation. Such kind of product has been widely used to estimate emissions, to monitor pollution hot spot as well as cross country and intercontinental transport. Within this work we have merged the column measurements of nitrogen dioxide with the simulations of the Transport Chemical Aerosol Model (TCAM) to improve the model output at the ground level. The method used is a weighted rescaling of the model column in the troposphere according to the SCIAMACHY observations where the weights are the measurement errors and the model column variances within the satellite ground-pixel, respectively. The employed data are related to the Northern Italy area. The obtained ground concentrations of NO2 have been compared with in-situ observations performed by the regional environmental agencies. Results show good agreement mainly where well horizontal mixing is present. The ground concentration from SCIAMACHY-TCAM gives an average NO2 amount within the satellite ground-pixel of 30x60 km2 that is important information for air quality assessment on a regional and/or national scale not easy to obtain only with ground-based observations. Our conclusions thus stress also the actual potential role of satellite observations combined with regional CTM models in the context of air quality monitoring, mainly in rural area, where the ground-based observations are missing

Sistema de evaluación de la dispersión episódica de contaminantes atmosféricos

Frente a la contaminación de otros medios (aguas, suelos), en la era preindustrial se había considerado a la atmósfera como un medio de depuración de contaminantes suficientemente eficaz como para que, salvo en contadas excepciones, las emisiones de contaminantes a la atmósfera resultasen inocuas para el medio y las personas; reduciéndose a un problema de molestias (olores, visibilidad), sin mayores consecuencias. Esta consideración errónea agudizó el problema de la contaminación atmosférica con la introducción de la máquina de vapor, origen de la revolución industrial, para cuyo funcionamiento comenzaron a quemarse grandes cantidades de carbón; a lo que hay que sumar el uso de otros combustibles fósiles en la industria y transporte, el manejo y emisión de sustancias procedentes de la industria química, y de otras actividades humanas. A partir de ese momento, la preocupación por la calidad del aire que respiramos ha ido pareja al reconocimiento de las incertidumbres en los procesos atmosféricos que afectan a los contaminantes, de carácter altamente no lineal y que experimentan grandes variaciones en función de la dinámica meteorológica, ya de por sí compleja. Estos procesos complejos, sin embargo, son los que permiten la depuración de los contaminantes en la atmósfera y, en consecuencia, la minoración de su impacto; por lo que se ha reconocido la necesidad de conocerlos y, cuando era posible, cuantificarlos. Así que, el conocimiento de los procesos atmosféricos relacionados con la contaminación atmosférica partió inicialmente del análisis de datos experimentales de campo, de una parte, y de modelos teóricos de los procesos atmosféricos y su posible relación con la dispersión física de los contaminantes. La simplicidad de las soluciones analíticas de dichos modelos teóricos, sin embargo, dificultaba su aplicación a problemas reales

EMEP Particulate Matter Assessment Report

This EMEP PM Assessment Report addresses the adequacy and completeness of the underpinning science upon which models currently used for policy development have been built. An important issue has been to strike a balance between the need to resolve a number of key scientific uncertainties and the desire to make progress with the integrated assessment modelling. It has been recognised that striking this balance is important for policy-making within the Working Group on Strategies and Review. The purpose of the report is to inform the policy process about the state of current understanding on PM issues and the level of confidence in PM models.JRC.H.2-Climate chang

GAMES, a comprehensive GAS Aerosol Modelling Evaluation System

In this work the modelling system GAMES is described. It consists of the transport and chemical models CALGRID and TCAM, the meteorological model CALMET, the emission evaluation model POEMPM, the boundary and initial condition module (BICM) and the system evaluation tool (SET). GAMES has two configurations to estimate ozone exposure and to analyze photochemical and aerosols pollution episodes. The system has been designed, implemented and tested over a Northern Italy domain by the Environmental System Modelling and Control research group of Brescia University in the frame of EUROTRAC2-SATURN project

GAMES, a comprehensive Gas Aerosol Modelling Evaluation System

(R.S. Sokhi and J.Brechler Editors), Published by the University of Hertfordshir