Dimiter Yordanov

Study of the pollution exchange between Bulgaria and northern Greece

The present work aims at a detailed study and explanation of the pollution transport in the air basin over south-western Bulgaria and northern Greece and assessment of the air pollution exchange between Bulgaria and Greece. Some well-known specific climatic air pollution effects were studied and explained. Calculations were made of the SO2 pollution of the Balkan Peninsula from both Greek and Bulgarian sources for 1995, and the country-to-country pollution budget diagrams were built. Days with extreme mean concentration for Bulgaria and northern Greece were picked out, and some further specification of the contribution of the different sources in both the countries to these cases of extreme pollution was made. Some preliminary studies of possible mesoscale effects on the pollution exchange between Bulgaria and northern Greece were carried out. A three-layer pollution transport model with a more complex chemistry block was introduced, and some preliminary simulations of the transport of sulfur and nitrogen...

On the stationary electric field in the air surface layer

SummaryThe solution of the ionization balance equation is found in the surface air layer at horizontal homogeneity assuming an exponential law for the turbulent diffusion coefficient. Expressions describing the vertical distribution of the small ion concentration are found estimating on their basis the layer height by an electrode effect. A relation is found among the small ion concentration, the electric conductivity and the electric field in the surface layer.

On turbulent diffusion from a steady line source in the surface layer under unstable stratification

SummarySolution of the diffusion equation is obtained for a linear source in the boundary layer with unstable stratification, when the Monin-Obukhov similarity theory is used for the wind profile and coefficient of vertical turbulent exchange. On the basis of the solution obtained numerically calculations are made.

The ABL Models Yordan and Yorcon — Top-Down and Bottom-Up Approaches for Air Pollution Applications

Two atmospheric boundary layer (ABL) models developed in agreement with the similarity theory are applied: YORDAN - for stable and neutral conditions and YORCON - for convective cases. Both models consist of a surface layer and an overlying Ekman layer. The vertical profiles of the temperature, wind velocity and the turbulent exchange coefficient in the ABL can be obtained applying the models. A proper parameterization is developed in both cases applying the resistance laws for stable, neutral and convective conditions. The relation between the external and internal to ABL parameters are given by the resistance laws numerically solved in both models. The input parameters for the models are obtained from the experimental data applying two approaches: the first one (called “top-down” approach) uses data for the geostrophic wind and the potential temperature. The second one (called “bottom-up” approach) uses data from the surface meteorological observations.

Parameterization of Pbl Using Surface Data for Application in Dispersion Modelling

The aim of the present work is to determine the vertical profiles of wind velocity, temperature and turbulent exchange coefficient in the Planetary Boundary Layer (PBL) using data collected from the automatic meteorological stations. The automatic meteorological stations (recently introduced in the NIMH network) provide hourly measurements of the wind velocity at 10 m and atmospheric stability classes based on measurements of the wind pulsations.

Study of the Pollution Exchange between Bulgaria and Northern Greece

The present work is an overall report on an extensive joint study, aimed at a detailed study and explanation of the pollution transport in the air basin over South-western Bulgaria and Northern Greece and assessment of the air pollution exchange between Bulgaria and Greece. Some well known specific climatic air pollution effects were studied and explained. Calculations were made of the S02 pollution of the Balkan peninsula from both Greek and Bulgarian sources for 1995 and the country to country pollution budget diagrams were build. Days with extreme mean concentration for Bulgaria and Northern Greece were picked out and some further specification of the contribution of the different sources in both the countries to these cases of extreme pollution was made. Some preliminary studies of possible mesoscale effects on the pollution exchange between Bulgaria and northern Greece were carried out. A three-layer pollution transport model with more complex chemistry block was introduced and some preliminary simulations of Sulfur and Nitrogen compounds transport were performed....

Parameterization of PBL from the Surface Wind and Stability Classes Data

The aim of the present work is to determine the vertical profiles of wind velocity and turbulent exchange coefficient in the Planetary Boundary Layer (PBL). Here a simple but very effective PBL model is presented based on the similarity theory. As input to this model the internal to PBL parameters are needed. There are two ways to obtain these parameters from experimental data and they are called here “down-up” and “updown” approaches. The full description of the “up-down” approach is given in a number of papers by the same authors. It will be also presented here briefly. The main stress will be on the “down-up” approach allowing to obtain the wind and turbulence profiles using the data collected from automatic weather stations. Recently, such stations are introduced in the observational network of NIMH providing hourly measurements of the wind velocity at 10-m height as well as atmospheric stability classes (based on measurements of the horizontal wind pulsation). The proposed approach uses these data for determining the internal and external PBL parameters on the basis of the Similarity theory.

On the absolute maximal concentrations of polydispersive particles from a Gaussian plume model under unstable conditions

In the regulatory practice of most European countries when studying the air pollution by heavy particles, released by industrial sources, it is normally assumed that the particles have a constant gravity deposition velocity [1, 2]. Usually the particles are divided by their size in four intervals and a mean sedimentation velocity is determined for each interval. The present work aims at calculating the pollution concentration, accounting for the polydispersive nature of the admixture.

On the Relationship Between Synoptic Scale Parameters and Pasquill Stability Classes for the Purposes of Air Pollution Modeling

Quite often, for the tasks connected with environmental impact assessment it is necessary to estimate pollutant concentrations on the basis of standard meteorological data such as sunshine, cloud amount, and wind velocity using the Pasquill stability classes. They are usually determined from the atmospheric characteristics estimated near the ground surface using a table classification with 10 m wind velocity and insolation intensity (or cloud cover at night). These meteorological data are not allways available and they are difficult for prognostication. For the purposes of the prognostical estimation of the atmospheric diffusion in case of emergency releases when regulatory type models are used it is useful to find the relation between the synoptic scale parameters obtained from the numerical weather prediction and the Pasquill stability classes.

Distribution of the concentration at small and large distances from a steady line source in the surface layer under unstable stratification

SummaryThe solution about the concentration from a line source in the surface layer under unstable stratification obtained by us in [1]2 is investigated. A physical sense is given to the obtained simple asymptotic representations, determining on the basis of some numerical calculations the region of their applicability too.