Past Events

Second Workshop on
"Large-Scape Scientific Computations"
(LSSC)

June 2-6, 1999, Sozopol, Bulgaria

The Workshop, which was held in Bulgaria for the second time, was organised by the Central Laboratory for Parallel Processing (CLPP) of the Bulgarian Academy of Sciences (BAS), Sofia in co-operation with the Division of Numerical Analysis and Statistics of the University of Rousse. This Workshop has become a traditional event that takes place every second year, starting in 1997. The meeting brought together numerical mathematicians, engineers, physicists, chemists, etc. working in the field of scientific computing and its application to solve scientific and industrially oriented problems. Providing a forum for the participants (more then 80 coming from 18 countries in Europe, Asia and America) to meet and exchange ideas of common interest in an informal atmosphere, this meeting was again a success.

Eight Special Sessions were incorporated in the framework of the Second Workshop on LSSC.

Zahari Zlatev (National Environmental Research Institute, Roskilde, Denmark) and Krassimir Georgiev (CLPP-BAS, Sofia, Bulgaria) organised the Special Session on "Large scale computations in air pollution modelling". Nine talks were given within it.

Zahari Zlatev discussed the application of special sparse solvers in the chemical part of large air pollution models. He stressed on the numerical treatment of stiff ordinary differential equations systems arising after the space discretization procedure. Some numerical results obtained on parallel computers were presented and discussed.

Clemens Mensink (Centre for Remote Sensing and Atmospheric Processes, Mol, Belgium) gave a talk on multiblock domain discretization for urban and regional scale air pollution modelling, which aims at improvement of the quality of the physical domain discretization at low computational cost.

Alison Tomlin (University of Leeds, UK) spoke about low dimensional mainfolds and reduced chemical models for air pollution simulations. It was demonstrated that the dimension of a typical tropospheric chemical model is low (varying between six and nine) and therefore, by using lower dimensional representation of the chemistry, savings can be made in terms of the number of equations which need to be solved in the chemical submodel of a dispersion code.

Dimiter Syrakov (National Institute of Meteorology and Hydrology, BAS) presented some results from the long-term calculations of mercury pollution over Southeast Europe due to Bulgarian sources on the base of a simple parametrization scheme for Hg chemical transformation, deposition and re-emission, conjugated to the three dimensional Eulerian Dispersion model EMAP, developed in the frame of the Bulgarian contribution to EMEP (1994-1997).

Reneta Dimitrova (Institute of Geophysics, BAS) reported about some examples of the mesoscale topography effects on large-scale air pollution transport. She demonstrated that the topography heterogeneity in some of the synoptic situations effects not only the detailed air pollution field in the country, but also some large-scale pollution characteristics as the total pollution of the country, the pollution fluxes through the country borders, etc.

Ralf Wolke and Jorg Weickert (Institute for Tropospheric Research, Leipzig, Germany) discussed in their talks the efficiency of different time integration schemes in relation to the used horizontal resolution as well as the load imbalances in the parallel implementation of the multiscale atmospheric chemistry-transport model MUSCAT (coupled with a meteorological driver for updating wind fields, humidity, density and other input data, it computes the state of air pollution).

Tzvetan Ostromsky (CLPP, BAS) gave a talk on an economical estimation of the losses of crops due to high ozone levels. The Danish Eulerian Model has been used to get AOT40 (Accumulated exposure over threshold of 40 ppb) and some preliminary results illustrating the applicability of the algorithm for Bulgaria were presented.

Finally, Krassimir Georgiev presented a parallel version of the two dimensional Danish Eulerian Model based on partitioning of the computational domain into several subdomains (as a rule, the number of subdomains is equal to the number of processors available during the computations of one multiprocessor computer system). The developed software is portable for distributed memory parallel computers and clusters of workstations.

Past Events

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