E. M. Apostolov, D. Altadill – Fourfold solar cycle variation of the geomagnetic 13.5-day periodicity power and longevity 3
Abstract. The daily samples of the geomagnetic aa-index for 134 years, from 1868 to 2001, were investigated by means of time-segmented Lomb-Scargle normalized power spectra and autocorrelation functions with the purpose to look for long-term variations of half-solar rotation periodicity power and longevity. We present evidence for a strong fourfold solar cycle variation of the spectral power and occurrences of intervals, and their duration, in which the 13.5-day periodicity is phase coherent. We suggest that, according to the tilted solar dipole model, it seems to be likely that the long-term variations of the heliospheric current sheet tilt show the same behavior.
Key words: half-solar rotation period, Hale cycle, solar cycle variation, geomagnetic activity index aa.

V. Pilipenko, P. Nenovski, H. Tanaka – Detection and discrimination of VLF/ULF seismic-related electromagnetic emissions 13
Abstract. The conception of the discrimination of electromagnetic emissions possibly related to the seismic processes is discussed. Basic formulas relevant to estimates of expected electromagnetic field produced on the ground by mechanic-electromagnetic emitters in geophysical media are provided. The comparative elementary analysis of the structure of hypothetical electromagnetic disturbances, produced by a lithospheric source, and of common electromagnetic noises suggests some simple techniques for the discrimination of signals from those two sources during single-point ground observations. The suggested impedance method claims that the ratios between vertical and horizontal components for magnetic and electric wave fields could be used for signal discrimination. A comparison of the electromagnetic field structure excited by probable lithospheric source and atmospheric/ionospheric source indicates that the best chance to reveal an anomalous emission can be obtained with either a horizontal electric antenna, underground vertical electric antenna, or vertical magnetic antenna.
Key words: ULF/VLF, electric field, magnetic field, antenna, polarization, impedance

B.V. Boytchev, P.I. Nenovski, St. T. Ivanov, M. Chamati, L. Petrov, V.B. Boytchev – Equipment for measuring quasistatic and ULF variations of the Earth electric potential 31
Abstract. An instrument for measurement of quasi-static and ULF variations of the Earth electric field measurements on the ground is designed and put in operation. By this apparatus a continuous monitoring of the ULF electromagnetic variations of lithospheric origin is realised. The analysis is preceded by an evaluation of the quality of data. The instrument dispersion reveals a high level of noise mainly during day hours. Additionally, there are days of high noise level which last diurnally. A preliminary FFT analysis of the data set is made.
Key words: Earth electric potential, seismoelectric signals, ULF electric and magnetic field, ULF variations, geomagnetic pulsations

N. Gromkova – Regulatory model for calculating of vehicles’ emissions, module EMISSIONS of software Traffic Oracle -PART I 42
Abstract. The software Traffic Oracle is a PC utility tool used for the purposes of the environmental policy in the development of road communications as well as for the impact assessments of vehicle emissions in the surface layer. The method developed, has been funded by the Bulgarian Ministry of Environment and Waters and the project outputs have been approved as a national regulatory standard. The program consists of two main modules – EMISSIONS and DIFFUSION. The first module calculates the emission estimates from the road transport based on the Joint EMEP/CORINAIR Atmospheric Emission Inventory Guidebook, Third Edition, Road Transport, Copenhagen, 2001. It has been assumed that emissions of burnt-out gases of motor vehicles in their motion along streets and highways can be approximated as continuous linear or area sources with finite length. The module package has been coded in Visual Basic and works under WINDOWS’ 9X, NT or XP. Its structure provides an easy way across the tasks, that the users have to carry out. The input information screen is user-friendly, and has well-provided-to warning messages of missing or restrictions to the supplied data.
Key words: regulatory model, air pollution, vehicle emissions, road transport.

N. Gromkova – Dispersion regulatory model for concentration of vehicles’ pollutants in the surface layer, module DIFFUSION of software Traffic Oracle – PART II 48
Abstract. The second module DIFFUSION of the software Traffic Oracle calculates the concentration of the vehicle pollutants from the road transport by the conventional Gaussian plume dispersion approach. It has been assumed that emissions of burnt-out gases from motor vehicles in their motion along streets and highways can be approximated as continuous linear or area sources with finite length The DIFFUSION module has two options concerning the input meteorological information: climate (wind roses) and time series. In both cases the meteorological input can be taken from ground observations or from synoptic data. The set of the mostly unfavorable meteorological conditions, at which the pollution from a given source configuration is maximal, can also be calculated, by varying the meteorological parameters. The software package has been coded in Visual Basic and works under WINDOWS’ 9X, NT and XP. Its structure provides an easy way across the tasks, that the users have to carry out. The input information screen is user-friendly, and has well-provided-to warning messages of missing or restrictions to the supplied data.
Key words: regulatory dispersion model, air pollution, road transport.

G. G. Tenchov – Evolution of the Earth gravitational field and the Earth-Moon system for the last 2Ga 54
Abstract. There exist various data for the length of the day derived by corals, bivalves, brachiopods and stromatolites. They indicate that the number of days per year in the last 2 Ga differs from nowadays. These data are covered by the third power polynomial equation. On the basis of this equation the following parameters in the geologic past (computed for every 200 Ma) are obtained: geometrical flatten of the Earth ellipsoid, the Moon distance, the period of the Moon rotation, radius of the Earth Equator, acceleration of the Earth gravitational force, relative change of the Earth tides. It follows that: 1.In the last 2 Ga the Moon was about two times closer to the Earth; 2.The tides from the Moon origin were about 6 times higher than now; 3.The Equatorial radius and the Earth gravitational field did not change substantially. These data can be used in further development of the theory of the long-term changes in the Earth history and related problems.
Key words: Earth gravitational field, Earth-Moon system.

R. Glavcheva, S. Dimitrova, I. Tzoncheva – The 2002 activation in Krumovo area, South Bulgaria, and related topics 65
Abstract. This study was provoked by a seismic activation in Central South Bulgaria, which started with a 4.2 magnitude event on the 5th of April 2002. The paper considers those seismic features of the 2002 earthquake sequence which alarmed the scientific community in Bulgaria. In order to elucidate the observed complex type of seismogenesis, the previous seismicity of the region of Activity-2002 has been examined searching for analogy. No similar earthquake series development has been found.
Key words: Central South Bulgaria, seismic series time development, present-day and long-term seismicity

E.Botev, B.Babachkova, B.Dimitrov, S.Velichkova, I.Tzoncheva, K.Donkova, S.Dimitrova– Preliminary data on the seismic events recorded by NOTSSI in July – December 2001
Abstract. A map of the epicentres of 838 earthquakes that occurred in te part of the Balkan Peninsula outlined by longitude l=190-300E and latitude j =370- 470N is presented. A more detailed analysis of the seismicity of the territory of Bulgaria and its adjacent lands is made.
Key words: seismicity

E.Botev, B.Babachkova, B.Dimitrov, S.Velichkova, I.Tzoncheva, K.Donkova, S.Dimitrova– Preliminary data on the seismic events recorded by NOTSSI in January – June 2002 82
Abstract. A map of the epicentres of 1010 earthquakes that occurred in te part of the Balkan Peninsula outlined by longitude l=190-300E and latitude j =370- 470N is presented. A more detailed analysis of the seismicity of the territory of Bulgaria and its adjacent lands is made.
Key words: seismicity

D. Solakov, S. Simeonova, L. Christoskov, L. Dimitrova – The EC MEREDIAN Project 91
Abstract. The EC MEREDIAN project (Mediterranean-European Rapid Earthquake Data Archive and Information Network) is presented. The main objectives and innovations of the project are stated. Additionally, the Bulgarian participation in MEREDIAN-2 is considered. When finished the MEREDIAN-2 project Bulgaria, as all other NAS countries (New Associated States from “former” Eastern Europe), should be a full member of the European earthquake data infrastructure and will take an active role in ongoing future infrastructure improvements.
Key words: data storage, data exchange, data analysis packages, BB network, data infrastructure.

New Books

Nikola Georgiev – Book Review 98