Catálogo de publicaciones - libros

Several splitting methods are used in the fields of applied mathematics. In this paper we construct a new operator splitting method, the so-called additive splitting, which is a first-order scheme and is parallelizable on the operator level. We perform numerical comparisons between the additive splitting and some other existing splitting schemes using different types of numerical methods. On a certain class of problems the new method gives better results than the traditional splitting methods of the same order, and proves to be competitive with the more expensive, higher-order splitting techniques. We see good possibilities to apply the new method in real-life air pollution models.

The ability to predict the measured crosswind spread of the plume as well as the centerline (maximum) concentrations in the urban environment based on tracer experiments was found generally to be within a factor of 2.

Urban air quality information originates either from observations or from mathematical tools — models and estimations. While the former correspond to the current status of air quality, and may be directly interpreted in terms of human health risk and eco-system degradation potential or effect, the latter provide forecasting information in advance, thus offering decision makers the opportunity to take preventive measures that would “smooth” or alter the results of a forecasted “episode” or even “crisis”. Both “information categories” have a strong spatial/temporal dimension, and are an ideal application domain for World Wide Web (Web)-based information dissemination methods. In the present paper, the use of web-based technologies for the management of environmental simulation tasks within the air quality domain is discussed.

The mathematical description of natural ventilation processes in quarries requires the updating of huge data bases. In order to describe air circulation in a quarry, the known mathematical model was adopted, which takes into account the process of thermal convection from natural as well as from artificial heat sources. The model includes the conventional Navier-Stokes, heat and mass transfer equations. In the hydrodynamic equation the buoyancy force was taken into account as well. The system of differential equations for describing the problem of free thermal convection in the quarry was treated numerically. The developed programs were used to obtain current estimations of the ventilation circuits in quarries in order to determine the pollution levels, needed for the forthcoming practical recommendations. We also examined the distance at which iron, nickel and cobalt spread from the quarry, and the effect of heavy metal pollution on the activity of certain soil enzymes.

We show in this paper possibilities offered by inverse modelling to improve the description of atmospheric dispersion of radionuclides in an emergency case. We describe how to couple models to observations in order to refine some input data such as source terms or certain physical parameters. We present our preliminary results obtained in synthetic experiments and indicate the directions of further studies leading to the capacity of adapting the parameter values on the basis of real observations. Two cases are investigated: the local scale (0-10 km) with the use of operational analytic models and the regional/continental scale with the use of 3D Eulerian models.

In the present paper, numerical simulation results are analysed in order to quantitatively assess the air pollution potential in Athens area during two days of diverse air quality and meteorological conditions, namely the 12 and 15 September 1994. During the 12 September, Athens was under the influence of Etesians while during the 15 the synoptic forcing was weak with the subsequent development of sea breezes. The results were produced using a 3-D, higher-order turbulence closure model, which has been previously validated against an extensive data set. The results revealed that the ventilation during the Etesian day is approximately half an order of magnitude larger than the respective one during the sea breeze day. This is attributed to large differences both in wind speeds and in boundary-layer depths. In addition, the results indicate that, during sea breeze days, Athens basin is prone to horizontal recirculation of pollutants.

An integrated assessment approach is presented to evaluate the impact of abatement strategies and mobility scenarios on transport emissions and urban air quality. The system consists of a set of flexible models that can be connected in a modular way within the framework of the impact pathway methodology. The MIMOSA model is used to evaluate road transport emissions. The AURORA model is used for urban air quality assessment and management. The evaluation of health impacts and environmental damage costs is carried out by applying the ExternE methodology.

The highest ozone concentrations in Slovenia occur in the southwest part of the country. This region has Mediterranean climate with a lot of sunshine during spring and summer. Ozone precursor emission in the western part of Slovenia is moderate. The main source of ozone precursor emission is traffic, emissions from other sources are small. Those emissions appear in the relatively narrow zone along the coast and the border with Italy. The area around the central part of the country is sparsely inhabited. The terrain there is rather hilly reaching 1500 m altitude. As opposed to this region, the emission of pollutants in the Po valley west from Gorica county is very high. This is one of the most industrialized regions in Europe. During the summer several episodes of photochemical smog are reported from big cities of North Italy where measures to abate pollution are introduced in case of such situations. Transport of pollutants across the border can be registered in the neighbouring countries. The main reason for the exceedances of the information threshold in the western part of Slovenia is the transport of pollutants. We have available good prediction of meteorological parameters in that area. To fulfil all demands of legislation regarding ozone concentration prediction, proper models should be chosen and adapted to these circumstances. More extensive monitoring will be performed for the validation of the models.

In the framework of the LIFE -Environment Program, The National Institute of Meteorology and Hydrology (NIMH) carries out a demonstrative project concerning with the urban impact of air pollution. The project Life ASSURE has focused on impacts of long term estimation procedures of pollution levels in the atmosphere, and in the surface and underground hydrologic environment in the context of urban panning. Thus, the ASSURE system is able to provide data for evaluating the pollution potential of each objective of urban planning, and to encourage or discourage those urban or industrial scenarios which could constitute a pollution risk for environment, and consequently to the population health. In the first part of this paper the way in which dispersion model results are integrated in the operational final system on the Open-GIS platform is described. In the second part of the paper the statistical performances of two dispersion models are presented.

The sophistication of air pollution modeling systems has continued to increase in the last decade. Nowadays, the complex numerical mesoscale meteorological and chemical dispersion models have become very robust tools which are quite sensitive to small changes in the atmospheric process. The use of these tools as air quality management systems is becoming more and more common at urban and regional levels in many parts of the world. In this contribution we have applied the MM5-CMAQ modeling system in the framework of OPANA V3 with emission data sets produced by EMIMO to evaluate the capability of the system to be used as a tool to determine in realtime and forecasting mode the individual impact of five different virtual industrial sources located at the south-east direction of Madrid (Spain) city. The system has been developed for two different scenarios for each single industrial source: OFF (complete switching off the emissions, 100%) and OFF50 (reducing the expected emissions from each single industrial source by 50%). The simulations are carried out over 120 hours, and the emission reduction strategies are applied for the last 48 hours in a way that when the system is used in real-time and forecasting mode in daily operational use, the information is ready to be applied 12 – 20 hours before the hour 96 of the simulation. So, implementation of the emission reduction strategy — in case of need — can be done for such a single industrial plant in such a period of time. The results of 11 simulations (ON + 5xOFF + 5xOFF50) are analyzed by developing a robust post-processing tool which will report us about the time, location (grid cell) and eventually the industrial plant (or plants) which should apply the reported emission reduction scenarios. The modeling system has been mounted with two domains for MM5 with 81 and 27 km spatial resolutions and also with other two domains with 9 km and 3 km spatial resolutions. The CMAQ model has been mounted according to MM5 architecture just for the domains with 9 and 3 km spatial resolutions. Analysis of the air quality impact of industrial sources is prepared for the domains with 9 km and 3 km spatial resolutions. The system has proved to be robust and sensitive enough to be used in a reliable way. The computer time for all exercises is about 140 hours on a PIV-3,06 Ghz. In real operational mode, it can be reduced to 14 hours or less (daily operation) with a 20 PC cluster.