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Urban population exposure forecast system to predict NO2 impact by a building-resolving multi-scale model approach.

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Title: Urban population exposure forecast system to predict NO2 impact by a building-resolving multi-scale model approach.
Authors: Veratti, Giorgio1 (AUTHOR) giorgio.veratti@unimore.it, Bigi, Alessandro1 (AUTHOR), Lupascu, Aurelia2 (AUTHOR), Butler, Tim M.2 (AUTHOR), Ghermandi, Grazia1 (AUTHOR)
Source: Atmospheric Environment. Sep2021, Vol. 261, pN.PAG-N.PAG. 1p.
Subject Terms: *Urban density, City dwellers, Multiscale modeling, Population forecasting, City traffic, Hybrid systems
Geographic Terms: Modena (Italy)
Company/Entity: European Environment Agency , World Meteorological Organization
Abstract: Operational forecasting systems based on chemical transport models (CTMs) nowadays generally produce concentration maps with a resolution in the order of 2–5 km, very rarely exceeding the sub-kilometre scale. The main reason for this restriction is the prohibitive computing cost that a simulation covering an entire country would have if set-up with a resolution in the order of meters. In this paper a hybrid forecast system, relying on the WRF-Chem model coupled with the PMSS Lagrangian modelling suite, has been developed and applied for each day of February 2019, to predict hourly NO 2 and NO x concentrations with a spatial resolution of 4 m, for the urban area of Modena (a city located in the central Po Valley). Simulated meteorological fields (temperature, wind speed and direction) were assessed at three urban stations, compliant with WMO standards, and modelled concentrations were compared with measurements at two urban air quality stations located at background and traffic sites. Results show that meteorological variables are well captured by the hybrid system and statistical performances are in line with the benchmark values suggested by the European Environmental Agency and with similar case studies focusing on the same area. Modelled NO 2 and NO x concentrations, notwithstanding a slight underestimation mainly evident at urban traffic stations for NO x , present a large agreement with related observations. The NO 2 Model Quality Objective, as defined by Fairmode guidelines, was met for both the urban stations and the other statistical indexes considered in the evaluation fulfilled the acceptance criteria for dispersion modelling in urban environment, for both NO 2 and NO x concentrations. In the second section of the study, the population exposure to forecasted NO 2 concentrations has been evaluated adopting a generic model of dynamic population activity. The population was distributed at hourly time steps in specific urban micro-environments at the same resolution of the concentration maps (4 m) and the short-term exposure has been computed as the product between the population density in each model cell and related surface NO 2 concentrations. An infiltration factor was also applied to estimate indoor concentrations. The hybrid system was shown to be particularly suited for assessing short-term peak exposure in areas influenced by traffic emissions. On the other hand, due to the limited time spent by the population within traffic related environments, the long-term population exposure calculated by the hybrid system tends to be similar to the WRF-Chem stand-alone estimate. • Development of an hybrid Eulerian-Lagrangian forecasting system. • A comparison between the hybrid system and a standard CTM is presented. • The population exposure to forecasted NO 2 concentrations was assessed. • NO 2 exposure estimate based on dynamic population activity. [ABSTRACT FROM AUTHOR]
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Abstract:Operational forecasting systems based on chemical transport models (CTMs) nowadays generally produce concentration maps with a resolution in the order of 2–5 km, very rarely exceeding the sub-kilometre scale. The main reason for this restriction is the prohibitive computing cost that a simulation covering an entire country would have if set-up with a resolution in the order of meters. In this paper a hybrid forecast system, relying on the WRF-Chem model coupled with the PMSS Lagrangian modelling suite, has been developed and applied for each day of February 2019, to predict hourly NO 2 and NO x concentrations with a spatial resolution of 4 m, for the urban area of Modena (a city located in the central Po Valley). Simulated meteorological fields (temperature, wind speed and direction) were assessed at three urban stations, compliant with WMO standards, and modelled concentrations were compared with measurements at two urban air quality stations located at background and traffic sites. Results show that meteorological variables are well captured by the hybrid system and statistical performances are in line with the benchmark values suggested by the European Environmental Agency and with similar case studies focusing on the same area. Modelled NO 2 and NO x concentrations, notwithstanding a slight underestimation mainly evident at urban traffic stations for NO x , present a large agreement with related observations. The NO 2 Model Quality Objective, as defined by Fairmode guidelines, was met for both the urban stations and the other statistical indexes considered in the evaluation fulfilled the acceptance criteria for dispersion modelling in urban environment, for both NO 2 and NO x concentrations. In the second section of the study, the population exposure to forecasted NO 2 concentrations has been evaluated adopting a generic model of dynamic population activity. The population was distributed at hourly time steps in specific urban micro-environments at the same resolution of the concentration maps (4 m) and the short-term exposure has been computed as the product between the population density in each model cell and related surface NO 2 concentrations. An infiltration factor was also applied to estimate indoor concentrations. The hybrid system was shown to be particularly suited for assessing short-term peak exposure in areas influenced by traffic emissions. On the other hand, due to the limited time spent by the population within traffic related environments, the long-term population exposure calculated by the hybrid system tends to be similar to the WRF-Chem stand-alone estimate. • Development of an hybrid Eulerian-Lagrangian forecasting system. • A comparison between the hybrid system and a standard CTM is presented. • The population exposure to forecasted NO 2 concentrations was assessed. • NO 2 exposure estimate based on dynamic population activity. [ABSTRACT FROM AUTHOR]
ISSN:13522310
DOI:10.1016/j.atmosenv.2021.118566