Hristo Chervenkov

Some aspects of impact in the potential climate change on ozone pollution levels over bulgaria from high resolution simulations

According to the European Environment Agency (EEA), the ground-level ozone is one of the most serious air pollutants in Europe today. High levels of ozone can affect the respiratory system and increases morbidity and mortality, particularly in sensitive groups of the population. Ozone also damages vegetation, reduces crop yields and corrodes technological materials. Ozone pollution is pronounced in regions with strong photochemical activity, such as the Mediterranean basin and Balkan Peninsula. Due to its central location in the second region, Bulgaria may be considered as a hot-spot for ozone and representative of ozone effects on Balkan ecosystems. Ozone concentrations are highly dependent on environmental conditions, including temperature. It is thought to be likely that long-term changes in climate will affect levels of future ozone pollution. Based on the calculated and accumulated in NIMH - Bulgaria during the CECILIA WP7-program data, scope of the presented work is to investigate the changes in ozone pollution levels, expressed with some exposure indices, due to climate change in Southeastern Europe.

On the sulphur pollution over the balkan region

The EMAP (Eulerian Model for Air Pollution) model is used to estimate the sulphur pollution over the Balkan region for 1995. A sub-domain of the standard EMEP grid is chosen containing all 12 Balkan countries. The computational grid in this domain has a space step of 25 km, twice finer than the EMEP grid. The meteorological input to EMAP is the operational DWD Europa-Model product. This information is processed in a special way as to obtain input information to the PBL model YORDAN built in EMAP. The source input is the official sulphur emission data. This information is processed further as to obtain 25x25 km data for both Large-Point and Area sources. The calculations are made month by month having the last moment fields from the previous month as initial conditions for the next month. The boundary conditions are set to zero so the influence of the other European sources is not accounted for in this study. According to the EMEP methodology multiple runs are made setting every time the sources of various countries to zero. The impact of every Balkan country in sulphur pollution of all other countries for 1995 is estimated and commented. The results of calculation are compared with measurements.

On the Winter Wave Climate of the Western Black Sea: The Changes During the Last 115 Years

We present a study of the winter wave climate of the Western Black Sea with a focus on the annual maximums and the mean seasonal wave heights. We did a numerical simulation of the wave parameters in the Black Sea by the wave model SWAN for a period of 110 years. The input wind fields are from the atmospheric reanalysis ERA-CLIM. We also performed a hindcast for the period 1980–2015 using winds from the CFSR reanalysis. Extended winter (December–March) was studied. We also studied the characteristics of the pressure gradients in a larger region attempting to quantify this way the interaction of Mediterranean lows with blocking highs. No significant long term changes were found for any of the characteristics of the mean and extreme wave climate.

TVRegCM Numerical Simulations - Preliminary Results

The oncoming climate changes at the moment are the biggest challenge the mankind is faced with. They will exert influence on the ecosystems, on the all branches of the national economy, and on the quality of life. The climate changes and their consequences have a great number of regional features, which the global models cannot predict. That is why an operation plan for adaptation to climate changes has to be based on scientifically well-grounded assessments, giving an account of regional features in the climate changes and their consequences.

Precipitation Pattern Estimation with the Standardized Precipitation Index in Projected Future Climate over Bulgaria.

The expected reduction of the precipitation over many regions in a non-stationary climate is a major concern for Europe. Climate change has the potential to increase drought risk by subjecting areas with all natural, social and economic consequences. Thus it is of great interest to analyze future drought severity projected from the climate models in order to elaborate effective mitigation strategies. In the presented work the tendencies of the total precipitation for two 30-year time periods, 2021–2050 and 2071–2100, simulated at the National Institute of Meteorology and Hydrology (NIMH-BAS) in the frame of the CECILIA project with ALADIN Climate model are used. Intending to find the precipitation sums in these periods, the tendencies are superposed over the averages for the World Meteorological Organization (WMO) reference period 1961–1990, obtained from the E-OBS gridded data set. The Standardized Precipitation Index (SPI) is selected to quantify the drought conditions and is calculated for three time-scales: SPI-3 for each season, SPI-6 for the cold and warm halves of the year and SPI-12 for the whole year. The study suggests that the magnitude of the prevailing negative tendency over the domain, which is better expressed in the second 30-year period, leads only to insignificant change of the resulting SPI distribution patterns.

Sensitivity Study of Different RegCM4.4 Model Set-Ups – Recent Results from the TVRegCM Experiment

Abstract The oncoming climate changes will exert influence on the ecosystems, on all branches of the international economy, and on the quality of life. Global Circulation Models (GCMs) are the most widespread and successful tools employed for both numerical weather forecast and climate research since the 1980s. However, growing demands on accurate and reliable information on regional and sub-regional scale are not directly met by relatively coarse resolution global models, mainly due to the excessive costs affiliated with the use of the model in very high resolution. Regional Climate Models (RCMs) are important instruments used for downscaling climate simulations from GCMs. Main aim of the numerical experiment Tuning an Validation of Regional Climate Model (RegCM-TVRegCM) is to quantify the impact of some tunable factors in the RegCM set-up on the model outputs. Thus, on the first stage of the study, the skill of 20 different model configurations in representing the basic spatial and temporal patterns of the Southeast European (SE) climate for the period 1999-2009, is evaluated. Based on these outcomes, the present work is dedicated on more detailed inspection of the model set-ups with recognizable better performance. The Pearson’s correlation coefficient between the time series of the temperature and precipitation of the 6 most promising model set-ups and the E-OBS on monthly basis are calculated. The main conclusion is that this test does not reveal single one model set-up that definitely over performs the other considered ones.

Snow Cover Assessment with Regional Climate Model - Problems and Results

Climate modelling, either global or regional, is usually treated as a typical large-scale scientific computational problem. The regional climate model RegCM, well-known within the meteorological community, is applied in the study to estimate quantitatively the snow water equivalent, which is the most consistent snow cover parameter. Multiple runs for a time window of 14 consecutive winters with different model configurations, in particular with various initial and boundary conditions, have been performed, in an attempt to obtain most adequate representation of the real snow cover. The results are compared with stations’ measurements from the network of the National Institute of Meteorology and Hydrology. Generally all runs yield similar results, where the overall (i.e. over the whole time span) biases are acceptable, but, however, with large discrepancies in the day-by-day comparisons, which is typical for climate modelling studies.

Assessment of the Air Quality in Bulgaria - Short Summary Based on Recent Modelling Results

The European Union has developed an extensive body of legislation which establishes health based standards and objectives for a number of pollutants in air. An appropriate method for evaluating the air quality of a certain EU-country is to contrast the actual air pollution levels to the critical ones, prescribed in the legislative standards. This study, which is part of greater one, is focused of the pollutants of most concern - the ground level ozone, particulate matter, and the sulphur dioxide, which is still a problem in Southeastern Europe. High-resolution data from the Bulgarian chemical weather forecasting and information system for the last three years are used to compute certain pollutant levels, which are further compared with the critical ones, prescribed in the EU-legislation directives. The obtained results can be treated as objective pattern of the situation over Bulgaria in the end of the first decade of the present century.

Estimation of the Exchange of Sulphur Pollution in Southeast Europe

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.