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Abstract

the Retezat Mountains, this study discusses radiocarbon chronology and sediment accumulation rate changes in two sediment profiles in relation to lithostratigraphy, organic content, biogenic silica and major pollenstratigraphic changes. A total of 25 radiocarbon dates were obtained from sediments of two lakes, Lake Brazi (TDB-1; 1740 m a.s.l.) and Lake Gales (Gales-3; 1990 m a.s.l.). Age-depth modeling was performed on TDB-1 using calibrated age ranges from BCal and various curve-fitting methods in psimpoll. Our results suggest that sediment accumulation began between 15,124–15,755 cal yr BP in both lakes and was continuous throughout the Late Glacial and Holocene. We demonstrated that local ecosystem productivity showed delayed response to Late Glacial and Early Holocene climatic changes in the subalpine and alpine zones most likely attributable to the cooling effect of remnant glaciers and meltwater input. However, regional vegetation response was without time lag and indicated forestation and warming at 14,450 and 11,550 cal yr BP, and cooling at ca. 12,800 cal yr BP. In the Holocene one major shift was detected, starting around 6300 cal yr BP and culminating around 5200 cal yr BP. The various proxies suggested summer cooling, shorter duration of the winter ice-cover season and/or increasing size of the water body, probably in response to increasing available moisture.

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Central European Geology
Authors: Nada Horvatinčić, Jadranka Barešić, Ines Krajcar Bronić, Bogomil Obelić, Krisztina Kármán, and István Fórizs

Abstract

Radioactive isotope tritium (3H) and stable isotopes of hydrogen (2H/1H) and oxygen (18O/16O) were measured during 2010 in the Sava River, precipitation and groundwater at 3 monitoring wells and 1 production well of the Petruševec aquifer, close to the Sava River in the Zagreb area. Significant increase of 3H activity in the Sava River was observed in June, (200 ± 20) TU, and in groundwater of all wells with damped response (maximum 60 TU) and with delay of 3–5 months related to the Sava River. This increase was explained by release of tritiated water from the Krško Nuclear Power Plant, 30 km upstream from Zagreb in the beginning of June 2010. Stable isotope analyses showed similar range of δ2H and δ18O values for the Sava River and groundwater samples with higher variations in surface water. Differences in monthly variations of δ18O values between particular monitoring wells, together with 3H values, indicated different infiltration times of surface water of the Sava River to different wells of the Petruševec aquifer.

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Central European Geology
Authors: Attila Demény, Alexandra Németh, Zoltán Kern, György Czuppon, Mihály Molnár, Szabolcs Leél-Őssy, Mihály Óvári, and József Stieber

of the bomb peak, whose lack in VK-1 might be related to a hiatus. Finally, stalagmite VK-2 shows a clear sign of the bomb peak with about 3 years delay, although the pMC values are lowest in this sample. As a next step, all of the data and patterns

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Mekik C 1997: Tropospheric delay models in GPS. International Symp. On GIS/GPS, Istanbul, Turkey Mekik C. Tropospheric delay models in GPS. International

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VLBI observations at various stations all over the globe have been carried out since the beginning of the eighties. As VLBI allows to determine tropospheric parameters such as hydrostatic and wet zenith path delays stable and long time series of these parameters exist that can be used for climatological studies. From the wet zenith delays information about trends and periodic variations of the amount of water vapour in the troposphere can be obtained. For example a trend of ~+0.7 mm/year in the wet zenith delay will correspond to a trend of ~ +0.1 mm/year in precipitable water. For assessing the reliability of the linear trends and the amplitudes of annual and semiannual components, data from VLBI, GPS, and the ECMWF (European Centre for Medium-Range Weather Forecasts) were compared. Good agreement was found for the seasonal variations, though the linear trends showed some disagreement. Possible reasons for this disagreement are discussed. Finally, the effect of El Niño events on tropospheric mapping functions and on length-of-day time series is shown.

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The paper describes a procedure of the ionospheric total electron content (TEC) specification on-line over Europe intended to provide the vertical total electron content in an operational environment. TEC data are derived from the International Global Positioning System (GPS) Service for Geodynamics (IGS) signal phase and amplitude measurements at European ground station network. Specification here refers to the fusion and visualization of available observations into a map representation of the plasmaspheric-ionospheric state over Europe with a maximum delay of up to about 24 hours. It is designed for models of operations that include post-analysis and real-time.

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Three-moded random ionospheric HF channel of propagation has been investigated.  The description of the channel has been given in terms of the scattering function and the appropriate codes for numerical calculations allowed assessment of the relative contributions of different modes in the scattering of the full field have been developed. In particular, the effect of overlapping of these contributions in the scattering function has been studied in the domain of Doppler spread -- group delay time. The dependence of this effect on the bandwidth of the signal and the geometry of propagation was investigated.

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The Vrancea region, in the South-Eastern Carpathians (Romania), represents a unique case among the seismic areas in the world taking into account the extreme concentration and persistence of seismicity and tectonic stress field. Our goal is to show that the particular shape of attenuation and shear wave splitting properties can be interpreted in the light of the decoupling and slab retreat processes, which hypothetically induce a specific configuration of the upper mantle flow. Delamination and break-off processes combined with retrograde motion of the slab imply lateral asymmetry in flow geometry and geotectonic properties. Particularly relevant is the strike-parallel flow localized in front of the downgoing slab, in contrast with the steeply dip flow along the slab in the back side. The local upper mantle flows around the descending seismic active body explains the contrast of the seismic wave attenuation in the back-arc region against fore-arc region and the strong anisotropy anomaly observed in the South-East Carpathians (time delays of 1.5–2 s). Outside the epicentral area, the coherent pattern of the shear wave splitting follows the trends of the deformation field as outlined by the GPS measurements, in favour of a strong coupling between the surface and mantle processes.

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Computational time is an important matter in numerical aspects and it depends on the algorithm and computer that is used. An inappropriate algorithm can increase computation time and cost. The main goal of this paper is to present a vectorization algorithm to speed up the global gradiometric synthesis and analysis. The paper discusses details of this technique and its very high capabilities. Numerical computations show that the global gradiometric synthesis with 0.5° × 0.5° resolution can be done in a few minutes (6 minutes) by vectorization, which is considerable less compared to several hours (9 hours) by an inappropriate algorithm. The global gradiometric analysis of representation by spherical harmonics up to degree and order of 360, can be performed within one hour using vectorization, but if an inconvenient algorithm is used it can be delayed more than 1 day. Here we present the vectorization technique to gradiometric synthesis and analysis, but it can also be used in many other computational aspects and disciplines.

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The kinematical behavior of points on an area of geodynamical interest is analyzed in a low — dimensional Riemann phase space in contrast to classic approaches that operate in time or frequency domains or in physical space. The phase space is reconstructed from series derived from regularly repeated GPS measurements that were transformed into a unified terrestrial frame. For the reconstruction the time-delay method was used, a concept in nonlinear time series analysis as developed by Packard (Packard et al. 1980) and proved by Takens (Takens 1981). The underlying dynamical model is a Hamiltonian motion equation so the reconstructed space is extended according to holonomic conjugated Hamiltonian coordinates. The GPS measurements are selected from a small area of geodynamical interest after its investigation based on analysis of raw geoidal signals (Doufexopoulou et al. 2006). Points from a neutral zone are used also for comparison purposes.The investigation aims to show that there exist significant differences in essential features of the chaotic behavior of the dynamical systems derived from the points of geodynamical interest and those from the neutral zone (in level of determinism and stability, in attractors, etc.). The method can be used to detect and investigate areas with geodynamical interest where already exist time dependent GPS measurements and at a large, continental scale.

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