This article describes the governing equations, computational algorithms, and other components entering into the Community Multiscale Air Quality (CMAQ) modeling system. This system has been designed to approach air quality as a whole by including state-ofthe-science capabilities for modeling multiple air quality issues, including tropospheric ozone, fine particles, acid deposition, and visibility degradation. CMAQ was also designed to have multiscale capabilities so that separate models were not needed for urban and regional scale air quality modeling. By making CMAQ a modeling system that addresses multiple pollutants and different spatial scales, it has a “one-atmosphere” perspective that combines the efforts of the scientific community. To implement multiscale capabilities in CMAQ, several issues (such as scalable atmospheric dynamics and generalized coordinates), which depend on the desired model resolution, are addressed. A set of governing equations for compressible nonhydrostatic atmospheres is available to better resolve atmospheric dynamics at smaller scales. Because CMAQ is designed to handle scale-dependent meteorological formulations and a large amount of flexibility, its governing equations are expressed in a generalized coordinate system. This approach ensures consistency between CMAQ and the meteorological modeling system. The generalized coordinate system determines the necessary grid and coordinate transformations, and it can accommodate various vertical coordinates and map projections. The CMAQ modeling system simulates various chemical and physical processes that are thought to be important for understanding atmospheric trace gas transformations and distributions. The modeling system contains three types of modeling components (Models-3): a meteorological modeling system for the description of atmospheric states and motions, emission models for man-made and natural emissions that are injected into the atmosphere, and a chemistry-transport modeling system for simulation of the chemical transformation and fate. The chemical transport model includes the following process modules: horizontal advection, vertical advection, mass conservation adjustments for advection processes, horizontal diffusion, vertical diffusion, gas-phase chemical reactions and solvers, photolytic rate computation, aqueous-phase reactions and cloud mixing, aerosol dynamics, size distributions and chemistry, plume chemistry effects, and gas and aerosol deposition velocity estimation. This paper describes the Models-3 CMAQ system, its governing equations, important science algorithms, and a few application examples. This review article cites 114 references. DOI: 10.1115/1.2128636

Review of the Governing Equations, Computational Algorithms, and Other Components of the Models-3 Community Multiscale Air Quality (CMAQ) Modeling System

. Tropospheric trace gas and aerosol pollutants have adverse effects on health, environment and climate. In order to quantify and mitigate such effects, a wide range of processes leading to the formation and transport of pollutants must be considered, understood and represented in numerical models. Regional scale pollution episodes result from the combination of several factors: high emissions (from anthropogenic or natural sources), stagnant meteorological conditions, kinetics and efficiency of the chemistry and the deposition. All these processes are highly variable in time and space, and their relative contribution to the pollutants budgets can be quantified with chemistry-transport models. The CHIMERE chemistry-transport model is dedicated to regional atmospheric pollution event studies. Since it has now reached a certain level a maturity, the new stable version, CHIMERE 2013, is described to provide a reference model paper. The successive developments of the model are reviewed on the basis of published investigations that are referenced in order to discuss the scientific choices and to provide an overview of the main results.

/pdf/chimere-2013-a-model-for-regional-atmospheric-composition-3ymu214cn0.pdf

CHIMERE 2013: a model for regional atmospheric composition modelling

https://www.cnrm.meteo.fr/IMG/pdf/sarrat_2006_ae.pdf

Impact of urban heat island on regional atmospheric pollution

http://www.meas.ncsu.edu/aqforecasting/publications/Zhang_AQF_partI.proof.pdf

Real-time air quality forecasting, part I: History, techniques, and current status

Multiple satellite sensors are used to analyze physical processes that determine energy fluxes and their interaction at the urban surface. The study is based on summertime microclimate analyses of the Los Angeles and Paris metropolises. The method consists of deriving some parameters governing the surface heat fluxes, constructing statistics of thermal infrared images, and using a GIS to combine them with a landcover classification from SPOT-HRV multispectral images, and with data from intensive in-situ experiments. The average images reveal spatial and temporal variations of land surface temperature (LST), and distinct microclimatic patterns. The combined interpretation of the statistics images and of the landcover classification shows: (i) the effect of surface physical properties, especially in downtown business and industrial districts that display heat-islands larger than 7 °C; (ii) the temperating influence of water; (iii) the negative correlation between afternoon land surface temperature and normalized vegetation index, which confirms the cooling effect of urban parks; (iv) the correlation between variations of surface temperature and ozone concentration at diurnal and longer time scales.

Satellite multi-sensor data analysis of urban surface temperatures and landcover

Validation of a hybrid forecasting system for the ozone concentrations over the Paris area

. The "Etude et Simulation de la QUalite de l'air en Ile de France" (ESQUIF) project is the first integrated project dedicated to the study of the processes leading to air pollution events over the Paris area. The project was carried out over two years (summer 1998 to winter 2000) to document all types of meteorological conditions favourable to air quality degradation, and in particular to photo oxydant formation. The goals of ESQUIF are (1) to improve our understanding of the relevant chemical and dynamical processes and, in turn, improve their parametrizations in numerical models, and (2) to improve and validate existing models dedicated to pollution analysis, scenarios and/or forecasting, by establishing a comprehensive and thorough database. We present the rationale of the ESQUIF project and we describe the experimental set-up. We also report on the first experiments which took place during the summer of 1998 involving surface networks, and remote sensing instruments as well as several aircraft. Focusing on three days of August 1998, the relative contributions of long-range transported and locally-produced ozone to the elevated ozone concentrations observed during this period are discussed and chemistry-transport model preliminary results on this period are compared to measurements. Key words: Atmospheric composition and structure (pollution – urban and regional; troposphere – composition and chemistry) – Meteorology and atmospheric dynamics (mesoscale meteorology)

/pdf/measurements-and-modelling-of-atmospheric-pollution-over-the-tacnc4kkjd.pdf

Measurements and modelling of atmospheric pollution over the Paris area: an overview of the ESQUIF Project

[1] Tropospheric photooxidant pollution was investigated in detail for the first time over the Paris area during the Air Pollution Over the Paris Region (ESQUIF) project. From 1998 to 2000, 12 intensive observation periods (IOPs) were carried out. They represented various meteorological situations, all leading to strong polluted events over Paris and its surroundings. During these periods, measurements were performed with a new strategy of circular flights around the city, coupled to stations or remote sensing surface measurements. Such data obtained at various altitudes and at different ranges from the city center document the evolution of pollution events on horizontal and vertical scales. In addition, ESQUIF also allowed for the evaluation of models developed in parallel to the project. In this overview, ESQUIF is presented in terms of the set of IOPs. Periods are compared in terms of meteorology and resulting types of pollution episodes. The occurrence of these latter events is discussed in terms of local production and influence of long-range transport. Using both measurements and model simulations, some important results are highlighted, especially concerning accuracy of boundary conditions, processes of mixing within the boundary layer, surface emissions estimation (including biogenic), and photolysis attenuation. Finally, results from data assimilation studies and sensitivity studies using adjoint modeling and a Monte Carlo approach are also presented.

http://www.lmd.polytechnique.fr/~menut/pp/2003-JGR-Vautard-Esquif.pdf

Dominique Gombert

Papers

Validation of a hybrid forecasting system for the ozone concentrations over the Paris area

Measurements and modelling of atmospheric pollution over the Paris area: an overview of the ESQUIF Project

A synthesis of the Air Pollution Over the Paris Region (ESQUIF) field campaign