Catálogo de publicaciones - libros

A three-dimensional numerical model of atmospheric hydrodynamics, transport and photochemical transformation of gas-phase pollutants and aerosol dynamics is considered. New particle formation occurs via binary homogeneous nucleation of sulphuric acid and water vapor, proceeding under the conditions of temperature and humidity fluctuations. The kinetic processes are described by multidimensional equations of condensation and coagulation, where the size-distribution function is given explicitly. Wind flow fields and turbulent characteristics are calculated from the mesoscale nonhydrostatic model of atmospheric hydrodynamics over complex topography. A series of numerical experiments are performed aimed at modeling the photochemical air pollution and aerosol dynamics in two specific regions as well as formation of sulfate aerosol particles in the northern hemisphere. A comparison is given for calculated and measured ozone concentration data.

In the paper we describe an air pollution model as applied to a composting plant. Two technologies of the composting process are compared. The model is based upon the Hungarian National Standards. The region is analyzed from meteorological and geomorphologic points of view. For illustration we add grayscale maps of relative concentration for three cases.

In this study we focus on the lowest part of the urban boundary layer, which is connected to a horizontal scale of 2–3 km and a vertical scale covering the surface boundary layer. The structure of the urban surface boundary layer is discussed with an emphasis on the turbulence parameters controlling dispersion processes in it.

Model estimations are presented on the annual average atmospheric concentrations and depositions of sulfur and nitrogen species, as well as on toxic elements in Hungary and its surrounding regions. Spatial and temporal variations of the distributions are discussed in the paper. The temporal variation of atmospheric sulfur budget was calculated based on a simple box model. In the case of Pb, the cumulative atmospheric depositions were also estimated for the period of 1955–2015. It was found that Hungary belongs to the moderately polluted regions in Europe. It is also demonstrated that significant part of tropospheric ozone and its precursors are imported to Hungary through longrange atmospheric transport processes.

In the present paper the exchange of sulphur pollution between 12 countries in Southeast Europe for 1995 is estimated. As only sources from these countries are handled, the results can be treated as an estimate of their mutual pollution and their impact on the acidification of the region. The results of such calculations can be used in decision-making, negotiating and contamination strategies development.

Eulerian-based air quality models encounter a serious numerical problem in solving the advection equation. In addition, mass conservation is often violated when meteorological model output is used as input to air quality models. The Trajectory-Grid algorithm handles the advection and eddy-diffusion in the Lagrangian and Eulerian framework, respectively. It is very accurate and can be used to trivially solve the advection equation for mixing ratios to address (but not correct) the mass conservation issue. We incorporated the algorithm into the state-of-the-science Comprehensive Air Quality Model with Extensions (CAMx). Applications of the model reveal the inaccuracy of the commonly used Bott advection scheme, and the subsequent compensating errors of the model. The results clearly call for a more reliable description of eddy diffusivity and emissions inventory in order to truly improve the reliability and predictive capability of air quality models.

The modeling of air pollution parameters is an issue investigated using different techniques. The pollution time series, however, are not continuous and contain gaps. Therefore, methods to infill the gaps providing satisfactory estimations are quite significant. In the presented study two ANN methods, feed forward back propagation, FFBP, and radial basis functions, RBF, were presented to estimate the SO2 values using the NO and CO values. It was seen that both ANN methods provided superior performances to conventional multi linear regression, MLR, method. The ANN performances were found satisfactory considering the selected performance criteria and the testing stage plots.

For solving numerically the partial differential equations describing air pollution transport, numerical methods are usually applied together with operator splitting procedures. In the present paper the interaction between operator splitting procedures and numerical methods is investigated by analytical and numerical study of the order of the error oppressing the numerical solution.

This study analyzes some mathematical aspects of data assimilation for atmospheric chemistry models based on variational approaches. Of interest here are the so called adjoint methods which are particularly efficient to mathematically solve the variational problem. Details concerning operator splitting, adjoint and gradient computations are also discussed.

High pollution levels may cause different damages. Therefore, critical levels have been established by different authorities (such as WHO, EU and environmental agencies in many countries). The critical levels should not be exceeded in the efforts to avoid damaging effects from harmful pollutants. Mathematical models can potentially be very useful tools when efficient measures have to be taken in order to bring the pollution levels under the prescribed critical levels and/or to keep them there. However, there are still many unresolved problems connected with the application of mathematical models in the attempts to design reliable and robust control strategies for reduction of the pollution to the critical levels and/or for keeping the pollution under the prescribed critical levels. Three of the unresolved problems, which are very challenging, will be discussed in this paper.