B.L.B. Wiman, E.H. Donev, P. N. Nikolova, L.D. Yurukova – Temperature investigations in Polyanovo hydrothermal reservoir (se Bulgaria)
Abstract. Much knowledge is lacking with respect to atmospheric trace-element concentrations in Bulgaria. We here report from a study of aerosol-borne concentrations of Al, Si, P, S, Cl, K, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Zr, Mo, Cd, Hg, Ag, and Pb in the southern Bulgarian Black Sea region and in the high-elevation Rhodope and Rila mountains. Our findings are novel for these regions. Time-weighted concentration levels (ng m-3) at the coastal site were for S, Si, Ca, Cl, Fe, and K in the range 100 to 1000; Zn, Al, Br, P, and Ti 10 to 100; Pb, Mn, V, Cu, Cd, Ag, and As 1 to 10; while Zr, Cr, Ni, Hg, Co, Se, Rb, Zr, Mo, Ge, and Ga were below 1. S, Cl, V, Zn, and Se levels were higher at the coastal site (Cl by a factor 20). Si, Ca, Cl, Fe, Al, Ti, and Sr were coarse-fraction oriented, and S, Zn, P, Pb, V, As, and Se fine-fraction oriented, at the coastal site. Similar features characterised the mountain sites; however, Cl and K at the Rila mountain site were fine-fraction dominated, Zn at the Rhodopes site was coarse-fraction oriented. We compare our findings with results from other studies in marine and mountain environments, and with general ranges commonly used to indicate whether regions are of remote, rural, or urban type. Levels found at our sites fall in the categories “remote” and “rural”; in some cases (Co, Ni, Cd, Hg) “urban”. Our results hold opportunities for source-region identifications and for input to deposition models. However, substantial further research is needed to assess these and other pressing problems with Bulgarian air quality and forest vitality.
Key words: macro and micro-constituents, heavy metals, Black Sea, Rila and Rhodopes Mountains

A. P. Anufriev – Approximation of incompressible fluid to the geodynamo convection

Abstract. The problem of applying the Boussinesq approximation to the convection in the Earth’s core is discussed. It is shown that the Boussinesq approximation neglects the essential part of the heat transport in the core, the adiabatic heat flux, which does not vanish in the incompressible limit. It also neglects the cooling due to the work of the Archimedean force. As a result, the law of energy conservation reduces to the heat conservation only. Thus, the Boussinesq approximation is inadequate for describing of the Earth core convection. Therefore we propose here a new, Incompressible approach, which takes all these effects into account. In the frame of this new approach we estimate the “natural” units for the Earth’s core convection. On this base we redefine the value of the Rayleigh number which is widely discussed in literature.
Key words: anelastic convection, Boussinesq approximation, geodynamo, compressibility

A. Todorova, G. Gadjev – Interaction of air pollution transport scales – outlines of studies in Bulgaria
Abstract. The smaller scale processes impact on larger scale air pollution patterns is a problem still far from being solved. The problem becomes even more difficult, but also more important in regions with complex terrain, like Bulgaria. That is why quite extensive studies on the subject had been carried out in our country. A brief review of these studies and some generalization of the conclusions made is the subject of the present work.
Key words: air pollution, atmospheric dynamics, transport scales, nesting, telescopic approach, mesoscale effects

E. Syrakov, M. Tsankov, J. Bonewitz – Influence of topography and thermal factors in the PBL on cyclone and anticyclone surface trajectories
Abstract. It is explored the influence of orographic and thermal nonhomogeneities and the friction in PBL on the trajectories of the baric formations (cyclones and anticyclones). It is explored their deviation from the conventional rule of the leading flow at level 500 hPa. On the basis of comparison with real synoptic situations it is shown that the used parameterization of PBL significantly improves the results.
Key words: orographic and thermal nonhomogeneities, parameterization, trajectories of the baric formations.

N. Rachev – Intercomparison of surface heat and water fluxes for the Adriatic sea between ECMWF re-analysis (ERA-40) and climatological data sets
Abstract. Using monthly means for the period 1957-1987, the ERA-40 pseudoclimatological heat and water fluxes have been assessed for the Adriatic Sea basin and have been compared with climatological data sets. It is shown that the shortwave and latent heat fluxes of the ERA-40 are underestimated compared to the climatological ones. This results in overestimation of the annually averaged total heat fluxes. The ERA-40 precipitation and evaporation are underestimated, also. The analysis shows that the ERA-40 heat and water fluxes can not be used in their original form to force a general circulation model for the Adriatic Sea. A simple correction procedure is applied in order to compensate the deviation of the ERA-40 surface fluxes from the climatological ones.
Key words: ocean/atmosphere interactions, weather analysis, Adriatic Sea.

N. Rachev, R. Purini – Numerical simulations of the Adriatic sea autumn circulation

Abstract. This study presents the results of numerical simulations of the climatological Adriatic Sea circulation during the autumn. The simulations are carried out using the DieCAST ocean model. The sensitivity of the model circulation to the different mechanical forcing is studied. The main Adriatic Sea circulation features are simulated properly. It is shown that during the autumn the wind forcing is of crucial importance only for the formation of the northern Adriatic circulation, whereas the thermohaline circulation is found to be more important over the rest of the basin. Numerical experiments show that the model is able to simulate well the outflow current through Otranto channel.
Key words: Adriatic Sea, general circulation ocean model.

L. D. Stoyanov, M.P. Grigorova – Estimation of atmospheric loading effects on site displacements of GPS-station SOFI
Abstract. It is performed an analysis focusing on the detection, estimation, separation and elimination of site offsets of permanent GPS-tracking station SOFI excited by atmospheric loading mainly. The seasonal atmospheric responses – total and degree-one spherical harmonic, of an elastic Earth’s deformation in cases of different data-meteorological and Earth’s mass centers are estimated. Here are analyzed the interactions of different atmospheric components with atmospheric rigid Earth’s translation and degree-one deformations and determined the role of periodic and local environmental (pressure and temperature) factors. It is proposed the hybrid models to regress vertical site’s variation field and the consistent with the frame treatment of the disturbing local atmospheric signals. The removing of these signals is being suggested to be done by inclusion of model predictions on the observation level in the analysis of GPS-observation or by correction of the time series after the analysis. The estimated degree-one deformations are being proposed for reduction of geometrically defined frames and time series to inertial origin. It is established for the first time for station SOFI the regression dependences between vertical site displacement and local pressure in case of different meteorological and Earth’s mass centers, the serious temperature periodic offsets in the North-South direction of station monument and the generating of 43% on vertical GPS-rate by the vertical atmospheric signal.
Key words: displacement, atmospheric loading, time series, degree-one deformation, Earth’s mass center

E.Botev, R.Glavcheva, B.Babachkova, S.Velichkova, I.Tzoncheva, K.Donkova, S.Dimitrova– Preliminary data on the events recorded by NOTSSI in July – December 2003
Abstract. A map of epicentres of 858 earthquakes that occurred in the Balkan Peninsula sector outlined by latitude j =370- 470N and longitude l=190-300E is presented. Expert generalized analysis of the seismicity over the territory of Bulgaria and its adjacent lands (with more than 490 localized events) is proposed.
Key words: Balkan Peninsula, Bulgaria, seismicity

E.Botev, R.Glavcheva, B.Babachkova, S.Velichkova, I.Tzoncheva, K.Donkova, S.Dimitrova– Preliminary data on the events recorded by NOTSSI in January – June 2004
Abstract. A map of epicentres of 858 earthquakes that occurred in the Balkan Peninsula sector outlined by latitude j =370- 470N and longitude l=190-300E is presented. A generalized analysis of the seismicity over the territory of Bulgaria and its adjacent lands (with 330 localized events) is proposed.
Key words: Balkan Peninsula, Bulgaria, seismicity

Венета Коцева– In Memorian: Angel Venedikov (1936–2007)