A comparison of the flood precipitation episode in August 2002 with historic extreme precipitation events on the Czech territory

The hydro-meteorological characteristics of the flood from August 2002, which affected a great part of the Czech territory, particularly the Vltava and Labe river basin, were compared with corresponding conditions during similar flood events in the summer seasons of 1997, 1890, 1897 and 1903. The comparison shows analogies in synoptic conditions and causal precipitation heights. The heaviest precipitation fell in the area of a considerable horizontal pressure gradient on the rearward side of the cyclone which advanced very slowly to the north-east across Central Europe and created conditions for the transport of moist air as well as for an organized long-term updraft enhanced in orographically exposed regions. The varying features of the individual events were based on the spatial–temporal distribution of causal precipitation and also on the very different saturation of the catchments. It was chiefly the extraordinary time concentration of precipitation together with the highest catchment saturation that made the flood in 2002 the most extreme.The extremeness of meteorological fields during two episodes in July 1997 was compared with two episodes in August 2002 with the aid of the reanalysis data from ECMWF. The first episode in 1997 and the second episode in 2002 were the most similar and more extreme in terms of the large-scale fields of basic meteorological quantities. The similar features of these episodes are specifically an intensive influx of moisture into Central Europe and intensive upward motions in the precipitation area. The extremeness of upper- and low-level potential vorticity fields was evaluated to diagnose the behavior of the cyclone and frontal precipitation bands accompanying it. The suitable spatial configuration of positive upper- and low-level potential vorticity anomalies induced an additional amplification of upward motions in the precipitation area that apparently contributed to triggering the heavy precipitation over Central Europe. On the whole, quantities reached more extreme values during the second episode in 2002.     

Geochemistry of highly saline fluids in siliciclastic sequences: genetic implications for post-Variscan fluid flow in the Moravosilesian Palaeozoic of the Czech Republic

Ubiquitous post-Variscan dolomites occur in Zn–Pb–Cu veins at the Nízký Jeseník Mountains and the Upper Silesian Basin (Lower and Upper Carboniferous siliciclastics at the eastern part of the Bohemian Massif). Crush–leach, stable isotope (oxygen and carbon) and microthermometry analysis of the fluid inclusions in dolomites enable understanding the geochemistry, origin and possible migration pathways of the fluids. Homogenisation temperatures of fluid inclusions range between 66 and 148°C, with generally higher temperatures in the Nízký Jeseník Mountains area than in the Upper Silesian Basin. The highest homogenisation temperatures (up to 148°C) have been found near major regional faults and the lowest in a distant position or at higher stratigraphic levels. Highly saline (16.6–28.4 eq. wt% NaCl) H₂O–NaCl–CaCl₂ ± MgCl₂ fluids occur in inclusions. Na–Cl–Br systematics of trapped fluids and a calculated oxygen isotopic fluid composition between ?0.9 and +3.0‰ V-SMOW indicate that the fluid was derived from evaporated seawater. Stable isotopic modelling has been used to explain stable isotopic trends. Isotopic values (δ¹³C = ?6.0/+2.0‰ V-PDB, δ¹⁸O = +15.5/+22.5‰ V-SMOW of dolomites) resulted from fractionation and crystallisation within an open system at temperatures between 80 and 160°C. Rock-buffering explains the isotopic composition at low w/r ratios. Organic matter maturation caused the presence of isotopically light carbon in the fluids and fluid–rock interactions largely controlled the fluid chemistry (K, Li, Br and Na contents, K/Cl, I/Cl and Li/Cl molar ratios). The fluid chemistry reflects well the interaction between the fluid and underlying limestones as well as with clay- and organic-rich siliciclastics. No regional trends in temperature or fluid geochemistry favour a fluid migration model characterised by an important vertical upward migration along major faults. A permeable basement and fractured sedimentary sequence enhanced the general nature of the fluid system. Fluid characteristics are comparable with the main post-Variscan fluid flow systems in the Polish (Cracow-Silesian ore district) and German sedimentary basins.     

Photometric observations of Earth‐impacting asteroid 2008 TC3

Abstract– A calibrated lightcurve is presented of the near‐Earth asteroid 2008 TC₃, obtained before it impacted Earth on October 7, 2008. The asteroid was observed in unfiltered images from the end of astronomical twilight until the object entered Earth’s shadow about 2 h later. The observations covered a wide range of phase angles from 14.79° to 2.93°, during which the asteroid ranged from 82,000 km to 29,000 km distance from the observer. A method is presented for obtaining photometrically filtered brightness values for the asteroid using unfiltered imaging techniques. Over 1,700 images of the asteroid produce a lightcurve with a peak‐to‐peak variation in V of 0.76 magnitude. Analysis of the lightcurve yields values for H = 30.86 ± 0.01 and G = 0.33 ± 0.03. Combined with other constraints on the kinetic energy and diameter of the asteroid, which suggest a low 1.8 g cm^?3 density and albedo 0.05 ± 0.01, the value of H implies an asteroid of about 4.1 m in diameter, 28 m³ in volume, and 51,000 kg in mass. The determined value of G is out of range for normal, larger asteroids of albedo 0.05–0.15.     

Radiation mechanisms and geometry of Cygnus X-1 in the soft state

We present X-ray/ γ -ray spectra of Cyg X-1 observed during the transition from the hard to the soft state and in the soft state by ASCA , RXTE and CGRO /OSSE in 1996 May and June. The spectra consist of a dominant soft component below ∼2 keV and a power-law-like continuum extending to at least ∼800 keV. We interpret them as emission from an optically thick, cold accretion disc and from an optically thin, non-thermal corona above the disc. A fraction f ≳0.5 of total available power is dissipated in the corona.
We model the soft component by multicolour blackbody disc emission taking into account the torque-free inner-boundary condition. If the disc extends down to the minimum stable orbit, the ASCA RXTE data yield the most probable black hole mass of M _X≈10 M_⊙ and an accretion rate,     , locating Cyg X-1 in the soft state in the upper part of the stable, gas-pressure-dominated, accretion-disc solution branch.
The spectrum of the corona is well modelled by repeated Compton scattering of seed photons from the disc off electrons with a hybrid, thermal/non-thermal distribution. The electron distribution can be characterized by a Maxwellian with an equilibrium temperature of kT _e∼30–50 keV, a Thomson optical depth of τ ∼0.3 and a quasi-power-law tail. The compactness of the corona is 2≲ℓ_h≲7, and a presence of a significant population of electron–positron pairs is ruled out.
We find strong signatures of Compton reflection from a cold and ionized medium, presumably an accretion disc, with an apparent reflector solid angle, Ω/2π∼0.5–0.7. The reflected continuum is accompanied by a broad iron K α line.     

Investigation of Times of Minima of Selected Early-Type Eclipsing Binaries

New precise times of minimum light for several early-type eclipsing binaries were obtained at three observatories. The changes of period of the following measured binaries are discussed: V1182 Aql, LY Aur, SZ Cam, FZ CMa, QZ Car, LZ Cen, V606 Cen, AH Cep and TU~Mus.     

Evaluation of meteorological controls of reconstructed rockfall activity in the Czech Flysch Carpathians

Rockfall is an important process in the final sculpturing of escarpments and scree slopes that originate in bedrock landslides in the Flysch Carpathians. The spatio‐temporal characteristics of rockfall activity were studied at four localities representative of old landslides in the highest part of the Czech Flysch Carpathians (Moravskoslezské Beskydy Mountains). Historical activity, chronology, and spatial context of rockfall activity were reconstructed using dendrogeomorphic techniques and rockfall rate index (RR). A total of 1132 increment cores from 283 trees growing in the rockfall transport and accumulation zones enabled the dating of 989 rockfall events. Reconstruction of a 78‐year‐long RR chronology suggests similar rockfall histories and trends at all study sites, indicating the existence of major common factors driving rockfall dynamics in the region. Temporal analysis and correlation of the RR series obtained with monthly mean temperatures, numbers of days with temperature transitions through 0 °C and monthly precipitation totals show that meteorological characteristics have evident but variable influence on rockfall activity. The most important factor is the effect of freeze–thaw cycles throughout the year, supplemented by low temperatures, especially during autumn. The influence of precipitation totals is of lesser importance. Copyright © 2011 John Wiley & Sons, Ltd.     

Comparison of global storm activity rate calculated from Schumann resonance background components to electric field intensity E0Z

This work presents the results of a comparison between the global storm activity rate I_RS and electric field intensity E_0Z. The permanent analysis of the I_RS may become an important tool for testing Global Electric Circuit models. I_RS is determined by a new method that uses the background component of the first 7 Schumann resonances (SR). The rate calculations are based on ELF observations carried out in 2005 and 2006 in the observatory station “Hylaty” of the Jagiellonian University in the Eastern Carpathians (Kułak, A., Zięba, S., Micek, S., Nieckarz, Z., 2003. Solar variations in extremely low frequency propagation parameters: I. A two-dimensional telegraph equation (TDTE) model of ELF propagation and fundamental parameters of Schumann resonances, J. Geophys. Res., 108, 1270, doi:10.1029/2002JA009304). Diurnal runs of the I_RS rate were compared with diurnal runs of E_0Z amplitudes registered at the Earth's surface in the Geophysical Observatory of the Polish Academy of Sciences in Świder (Kubicki, M., 2005. Results of Atmospheric Electricity and Meteorological Observations, S. Kalinowski Geophysical Observatory at Świder 2004, Pub. Inst. Geophysics Polish Academy of Sciences, D-68 (383), Warszawa.). The days with the highest values of the correlation coefficient (R) between amplitudes of both observed parameters characterizing atmosphere electric activity are shown. The seasonal changes of R, I_RS and E_0Z are also presented.     

Modeling and monitoring of mine water rebound in an abandoned coal mine complex: Siersza Mine, Upper Silesian Coal Basin, Poland

A variable-volume, head-dependent mine water filling model (MIFIM) has been utilized to simulate the post-abandonment flooding of the Siersza coal mine in the Upper Silesian Coal Basin of southern Poland. It is demonstrated that desaturated pore space in the aquifer adjacent to the mine comprises a significant component of the resaturable mine-related void. The model results are very sensitive to the value of this poorly constrained parameter. Nevertheless, the model successfully predicted the first appearance of mine water in an observation well and its subsequent rise. Despite this apparent success, it is concluded that such modeling approaches generally lack predictive power for mines in permeable, porous host rocks. As real monitoring data accumulate, however, such models can be calibrated and their utility increased.     

Geochemical facies model of ore formation in the Grythyttan-Hällefors area,Bergslagen, Central Sweden

The different iron and manganese ore deposits of the Grythyttan-Hällefors area display an arrangement that reflects a systematic change in redox conditions from oxidic banded iron formation into highly reduced graphite-bearing slates. This phenomenon is explained by a facies model. The different environmental conditions are also held to be responsible for the geochemical differentiation of base metal deposits into Cu ores associated with minerals of Bi, Co, Mo, As, Zn, Pb, Au, and Pb-Zn-Ag ores associated with minerals of Sb, Mn, As, Sn, Cu. Spatial relationships between deposits of these two groups and certain iron and manganese deposits point to a common source of all metals, possibly connected with exhalative derivates from basic volcanism.

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Zusammenfassung Die verschiedenen Eisen- und Manganerz-Bildungen des Grythyttan-Hällefors-Gebietes zeigen Verhältnisse auf, die einem systematischen Wechsel der Redoxbedingungen wiedergeben, von oxidischer Bändereisenerzbildung bis hin zu stark reduzierten graphitführenden Schiefern. Dieses Phänomen wird durch ein Fazies-Modell erklärt. Die unterschiedlichen Milieu-Bedingungen werden auch als Ursache für die geochemische Diferentiation unedler Metall-Ablagerungen in Cu-Erze angesehen, die mit Mineralien assoziiert sind, die Bi, Co, Mo, As, Zn, Pb, Au führen und in Pb-Zn-Ag-Erze in Verbindung mit Sb-, Mn-, As-, Sn- und Cu-führenden Mineralien. Die räumlichen Beziehungen zwischen Ablagerungen dieser zwei Gruppen und gewissen Eisen- und Mangan-Bildungen weisen auf eine gemeinsame Quelle aller Metalle hin, die möglicherweise mit exhalativen Derivaten eines basischen Vulkanismus in Verbindung steht.

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Résumé Les différents gisements de minerais de Fe et Mn de la région de Grythyttan-Hällefors montrent une disposition qui réflète un changement systématique dans les ernolitions de réduction des formations rubanées de fer oxydé en phyllades graphiteux. Ce phénomène s'explique suivant un modèle faciétal. Les différentes conditions de l'environnement sont ainsi rendues responsables de la différentiation géochimique des gisements métallifères de base en minerais de Cu associés à des minéraux de Bi, Co, Mo, As, Zn, Pb, Au et des minerais de Pb-Zn-Ag associés à des minéraux de Sb, Mn, As, Sn, Cu. Des relations spatiales entre les gisements de ces deux groupes et certains gisements de Fe et Mn indiquent une source commune pour tous les métaux, en liaison possible avec des émanations du volcanisme basique.

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