J. L. Pérez

Prediction of ozone levels in London using the MM5-CMAQ modelling system

Air pollution in urban areas has important implications for health and environmental management. Consequently, various methodologies have been developed for its assessment. Traditionally, simple approaches such as the box model or the Gaussian plume have been used to assess urban air quality. The use of Eulerian grid models, which provide a more realistic and comprehensive description of the urban atmosphere, has been increasing over the past few years. This paper reports on the use of the MM5-CMAQ modelling system to predict hourly ozone levels over London, UK. This work represents the first application of MM5-CMAQ in the UK for predicting air pollution levels in London. Domain resolutions of 9km, 3km and 1km (innermost) have been employed for this study. Summer periods in July and August 2002 have been simulated and the predicted results have been compared to several urban background stations across London. Input data for emissions have been derived from the UK National Emissions inventory and from the outputs of the EMIMO emission model. The CBM-IV chemical scheme has been used to simulate the atmospheric reactions for ozone. The model performance has been evaluated with measured data through a range of statistical measures. Although, the MM5-CMAQ model reproduces the ozone temporal trends it was not able to simulate the peak magnitudes consistently. Furthermore, for nighttime the model overestimated the ozone concentrations. The paper discusses the model performance and reasons for these discrepancies in terms of the various input data including emissions and meteorological parameters.

Air Quality Modeling

Air pollution modeling (APM) is being developed and used in order to better understand, investigate, assess, and regulate the quality of the atmospheric environment and the distribution of toxic pollutants which are often used in ecotoxicology. Atmospheric models are also used to assess the impact of air pollutants on human health. In this respect, APM covers a very complex and interdisciplinary scientific area, where aspects of environmental policy and decision making mix together with aspects like remote sensing, land-use impact, initial and boundary conditions, data assimilation techniques, chemical schemes, comparison methods between data measured and data modeled, computational efficiency and performance, coupling with the meteorology, long-range transport impact on local air pollution, new satellite data assimilation techniques, real-time and forecasting air quality modeling and sensitivity analysis, and many others. APM has progressed significantly during the last two decades, attracting the interest of various research groups and initiatives worldwide. It covers all aspects related to the life cycle of pollutants, starting from their emission or ‘production’ within the atmosphere, and ending with their impacts on man and the ecosystem. This field of science is interested to describe the generation, transportation, dispersion, physical and chemical transformation, and the impact of various categories of substances that are identified and classified as air pollutants via the environmental legal framework and the scientific community. It should be noted that air pollution is very much related to meteorological fields, since the atmosphere is governed by the general fluid mechanics laws described by the Navier–Stokes equation system, while progress in computer performance during the last decades has substantially impelled the research on air quality modeling in a parallel way. This contribution focuses on providing a general overview of the state of the art on air quality modeling, from the point of view of the ‘user community’, that is, policy makers, urban planners, environmental managers, etc. It also tries to bring to the discussion key questions concerning the air quality modeling success in usage, such as: identification of uncertainties in emission inventories and meteorological fields, capability of simulating pollutants like urban aerosols, the next-generation developments in models to answer new scientific questions, etc.

A modelling study of an extraordinary night time ozone episode over Madrid domain

AbstractDuring the early morning hours on April 29, 2000, a time series of ozone observations from several stations showed that a uniqueand exceptional ozone episode occurred in Madrid city and surrounding areas, whereby monitoring stations reported ozoneconcentrations up to 1190 mg/m 3 . In order to investigate this phenomenon, two different air quality modeling approaches are usedhere:U The FLEXTRA trajectory model was initially used, suggesting that an intrusion of stratospheric air occurred over the Madridarea and brought stratospheric air down to 1000e2000 m AGL. The local circulation system, not resolved by the FLEXTRAtrajectories, subsequently brought some of this stratospheric air to the surface. However, the maximum ozone concentrationthat could be explained by this process is much less than the observed one.U The OPANA Air Quality Modeling System was also employed to study air quality over the Madrid community and citydomains. Results suggested that the main wind direction returned to Madrid after 180( wind change direction 1 to 2 h beforethe ‘‘episode’’, bringing back ozone generated the day before (typical weekend day with high traffic density). On the other hand,convergence of winds along the South-West North-East axis over the Madrid community showed an important correspondencewith the sequence of observations.Preliminary conclusions show that the exceptional meteorological conditions on such a night could be reason for the occurrenceof high values. Additional technical circumstances (such as technical incidences in some monitoring stations) also suggest that someinstruments did not work properly under these high concentrations and, thus, real ozone concentrations may have been lower thanthose measured. 2004 Elsevier Ltd. All rights reserved.

The evaluation of the air quality impact of an incinerator by using MM5-CMAQ-EMIMO modeling system : North of Spain case study

The use of sophisticated air pollution modeling systems to evaluate the impact of different industrial plant emissions is currently done in an extensive way. MM5-CMAQ (PSU/NCAR and EPA, USA) is one of the most applicable air quality modeling systems to evaluate those impacts. In this contribution we present the methodology and results obtained when applying the MM5-CMAQ air quality modeling system for evaluating the potential impact of an incinerator in San Sebastián (Basque Country, Spain). We have used the EMIMO (UPM, Spain) emission model to simulate the emissions from biogenic and anthropogenic sources including traffic and tertiary sector sources. The study includes the air quality impact of a highway located near the incinerator named A8 and 6 industrial plants which already exist. The impact study has been compared with the results obtained from this highway impact and the 6 industrial plants which are normally operating during the last 30 years. The system has been prepared to simulate also Cadmium, Arsenic, Nickel, Lead and Benzo(a)pyrene air quality impacts. The PCDD/F air concentrations have been determined for the 16 toxic dioxins and furans as determined in the bibliography. The criteria pollutants such as CO, NOx, SO(2), PM(10) and O(3) have also been determined according to the different EU Directives which limit the values of such a pollutants for different periods of time.

Elevated PM10 And PM2.5 ConcentrationsIn Europe: A Model Experiment WithMM5-CMAQ And WRF-CHEM

We have applied the MM5-CMAQ model to simulate the high concentrations in PM10 and PM2.5 during a winter episode (2003) in Central Europe. The selected period is January 15 – April 6 2003. Values of daily mean concentrations up to 75 μgm are found on average of several monitoring stations in Northern Germany. This model evaluation shows that there is an increasing underestimation of primary and secondary species with increasing observed PM10. The high PM levels were observed under stagnant weather conditions that are difficult to simulate. The MM5 is the PSU/NCAR non-hydrostatic meteorological model and CMAQ is the chemical dispersion model developed by EPA (US) used in this simulation with CBM-V. The TNO emission inventory was used to simulate the PM10 and PM2.5 concentrations with the MM5-CMAQ model. The results show a substantial underestimation of the elevated values in February and March 2003. An increase on the PM2.5 emissions (five times) produces the expected results and the correlation coefficient increases slightly. The WRF/CHEM model results show an excellent performance with correct emission database. The main difference between MM5-CMAQ simulations and WRF/CHEM is the MOSAIC particle models and the “classical” MADE/SORGAM particle model used in WRF/CHEM and CMAQ respectively. MOSAIC seems to make a better job than MADE particle model for this particular episode.

A mesoscale study of the impact of industrial emissions by using the MM5-CMAQ modelling system

The scientific interest in improving the air quality tools that provide a detailed description – source oriented – of atmospheric processes and the impact of specific large industrial emission points is growing. This paper describes the results of using a state-of-the-art third-generation air quality modelling system (MM5-CMAQ) over a pilot test industrial site in the Madrid mesoscale domain. The MM5 model is a web-based non-hydrostatic mesoscale meteorological model developed by PSU/NCAR, and the CMAQ (Community Multiscale Air Quality Modelling System) is a third-generation air quality dispersion model developed by the US EPA. Both are modular codes and include an interface called MCIP, which assures full consistency with the numerical methods in the advection and diffusion schemes in the meteorological module and the chemistry and dispersion module. The application has been done with the CBM-IV chemical scheme (simple version). The results of running the so-called ON/OFF approach – in other words, the differences between the simulation with full industrial emissions and no industrial emissions – show that the MM5-CMAQ modelling system can be used as an excellent tool for evaluating the impact of different emission sources in an operational mode. Results also show that increases up to 50% on average and larger values for hourly impacts for ozone concentrations are found in the surrounding areas of the industrial plant. In addition, we see that the distance where the industrial emissions are impacting on the air quality can be larger than 40 km.

A Multi-model Case Study on Aerosol Feedbacks in Online Coupled Chemistry-Meteorology Models Within the COST Action ES1004 EuMetChem

The importance of different processes and feedbacks in online coupled chemistry-meteorology models for air quality simulations and weather prediction was investigated in COST Action ES1004 (EuMetChem). Case studies for Europe were performed with different models as a coordinated exercise for two episodes in 2010 in order to analyse the aerosol direct and indirect radiative effect and the response of different models to aerosol-radiation interactions.

Numerical modelling of 2003 summer forest fire impacts on air quality over Portugal

In 2003 Portugal faced the worst fire season ever recorded. The main purpose of this work is to evaluate the effects of the 2003 forest fires on the air quality, applying four numerical modelling systems (LOTOS-EUROS, MM5-CMAQ, WRF/chem and MM5-CHIMERE), and to compare their results with air quality data from several monitoring stations in Portugal. Forest fire emissions have been calculated taking into account the most suitable parameters for Portuguese forest/fire characteristics and the area burned by each forest fire. They were added to the anthropogenic and biogenic gridded emissions, according to the fire location and assuming a uniform fire spread and injection into the mixing layer. Simulations were performed during August 2003 regarding gaseous and particulate matter pollutants. To better evaluate the impact of forest fire emission on the air quality, a baseline simulation was performed, including the “conventional” emissions, along with a forest fire simulation, which also considered emissions from forest fires. Modelling hourly results, namely particulate matter (PM) and ozone (O3) concentration, values have been compared to measurement data at several monitoring locations. In general, the different modelling systems show a good performance, which improves when forest fire emissions are considered, particularly for the PM concentrations. The influence of the forest fire emissions in O3 formation is not so evident and needs more attention. The evaluation of the impact of forest fires on the air quality should be included in air quality assessment procedures, specifically in areas that

CFD and Mesoscale Air Quality Modelling Integration: Web Application for Las Palmas (Canary Islands, Spain)

The integration of sophisticated mesoscale air quality modelling systems, such as MM5-CMAQ and new generation of Computational Fluid Dynamics (CFD) modelling tools has been developed in this contribution. We have used an advanced and adapted version of the MIMO model (U. Karlsruhe, Germany) which is a sophisticated CFD model, to simulate the air concentrations at urban level with 10 m spatial resolution over the city of Las Palmas (Canary Islands, Spain). The CFD code receives the traffic emission data every second produced by a cellular automata model (CAMO). The integrated CFD model is called MICROSYS. This model is an Eulerian 3D tool which is running in diagnostic mode once every minute. The boundary conditions are obtained from the well-known MM5-CMAQ running over the city in prognostic mode. The MM5-CMAQ (OPANA V4) model is run with 1 km spatial resolution covering a domain of 16 × 16 km over the city. This system is operating in forecasting mode since 2004 and is operated over the Internet. The forecasting information for meteorology and air quality concentrations for the following 72 hours is used by MICROSYS to simulate the expected air concentrations at street level for the next three days. The system operates under daily basis and produces the detailed forecasting information at 6:00 GMT everyday. The Internet service includes a sophisticated VRML (Virtual Reality Modelling Language) tool to visualize in a 3D mode the air concentrations at street level by an Internet client. The VRML tool runs on the client server. We present also some comparative results related to the use of shared 64 bits memory machines and single 32 bits one-processor machines for CFD runs.

Chapter Fourteen Computational Air Quality Modelling

Abstract Progress in computer capabilities has substantially influenced research in air quality modelling, a very complex and multidisciplinary area. It covers remote sensing, land use impacts, initial and boundary conditions, data assimilation techniques, chemical schemes, comparison between measured and modelled data, computer efficiency, parallel computing, coupling with meteorology, long-range transport impact on local air pollution, new satellite data assimilation techniques, real-time and forecasting and sensitivity analysis. This contribution focuses on providing a general overview of the state of the art in air quality modelling from the point of view of the “user community,” which includes policy makers, urban planners and environmental managers. It also tries to bring to the discussion key questions, such as where are the greatest uncertainties in emission inventories and meteorological fields, how well do air quality models simulate urban aerosols, and what are the next generation developments in models to answer new scientific and management questions.